Authorities are investigating the beating by Alameda County sheriff’s deputies of a man accused of ramming patrol cars and leading deputies on a high-speed chase last week that ended in San Francisco, officials said. 
 
 The beating of the man, identified as Stanislav Petrov, occurred early Thursday morning and was caught on surveillance video and released on YouTube by the San Francisco public defender’s office, which said it received the footage from someone who operates a security camera in the area. 
 
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 The grainy footage shows two Alameda County sheriff’s deputies chasing a man on foot. As the man slows, one officer tackles him and punches him twice. The second officer arrives and starts hitting Petrov with his baton. Soon both officers can be seen hitting Petrov with their batons. Sometimes Petrov can be seen on the ground and other times on his knees. Once the officers begin striking him, he does not appear to be resisting. 
 
 In the video, the officers strike Petrov with their batons more than 30 times before other officers arrive on the scene. Some critics likened the episode to the infamous 1991 Los Angeles police beating of Rodney King, which led to bloody civil unrest in Southern California after officers were acquitted the next year of wrongdoing in a state trial. 
 
 In last week’s incident, “I was shocked by the brutality,” Tamara Barak Aparton, a spokeswoman for the Public Defender told The Times on Sunday. “He is clearly not resisting. And they hit him multiple times in the head with their batons. It doesn’t look like they’re trying to subdue him. It looks like they’re trying to punish him or trying to exact revenge.” 
 
 One witness was asleep in a third-floor apartment, about 60 to 70 feet away from where Petrov fell, when awakened by sounds from below. 
 
 “I heard people yelling,” said Matt G., who asked that his full last name not be used because he was concerned about calling attention to himself. 
 
 The witness, who was among the first to make contact with the public defender, said he saw about the last 15 seconds of the altercation from his window. 
 
 “Right when I looked out, he was on his knees with his hands trying to block the batons. Then he fell to the ground. It’s not that he was resisting. He was just trying to protect himself with his hands,” the man told The Times in an interview Sunday. “It looked like the officers were taking out aggression. The blows were hitting him all over. He was just trying to protect himself from getting brutally injured.” 
 
 When police backup arrived seconds later, he said, his view of the scene was blocked and he could see nothing else clearly. 
 
 Officers on duty Sunday said they had no information about the incident and could not comment on the case. The press officer for the Alameda County Sheriff's Department could not be reached. But on Friday, the department announced that it was launching an internal investigation. 
 
 No decision has yet been made about whether the two officers would return to duty or in what capacity. 
 
 KQED News quoted the department as reporting that the officers were veterans and would not be immediately identified out of concern for their safety. 
 
 “If you look on social media, there’s a lot of threats that have been made against them — pretty vulgar threats,” Sgt. Ray Kelly said. “We have to worry about their safety, in addition to Mr. Petrov in the hospital, too. We don’t want people showing up there, protesters showing up there and causing a whole bunch of problems.” 
 
 The station also reporting that, as of Sunday, Petrov remained at San Francisco General Hospital, where he was visited by Alameda County Public Defender Brendon Woods. 
 
 Woods told KQED that Petrov had suffered multiple cuts to the back of his head and that his arms were “crushed.” 
 
 “From his elbow through his hands are swollen,” Woods said. “It looks like he has several broken bones in both of his hands or arm areas.” 
 
 Petrov was alert and able to talk, Woods added. 
 
 Authorities have not released Petrov’s age or city of residence. But a woman whom KQED identified as Petrov’s mother said she and her son immigrated to San Francisco from Ukraine 18 years ago and that her son is 28. She said he has been diagnosed with multiple mental disorders, including post-traumatic stress and depression. She said he had suffered several concussions in the past. 
 
 Petrov faces felony charges for ramming a squad car and injuring a deputy, then leading a high-speed chase to San Francisco. He also is being held on suspicion of having a loaded firearm in the stolen vehicle he was driving, possession of methamphetamine and multiple hit-and-runs. 
 
 The incident began about 1:30 a.m. Thursday, according to the Sheriff’s Department. 
 
 Officers on patrol spotted what they believed to be a stolen 2015 Mercedes-Benz with Petrov at the wheel. As officers advanced, Petrov allegedly struck a patrol car, pushing it into a deputy, injuring the officer, Kelly told reporters. Petrov allegedly hit a second patrol car and then sped off, taking Interstate 580 through Oakland and then crossing the Bay Bridge into San Francisco, hitting speeds as high as 100 mph during the 40-mile pursuit. The chase ended, said Kelly, when Petrov hit a parked car in the Mission District and tried to run away. 
 
 Officers at the scene reported that they found a loaded gun in the Mercedes. 
 
 Another department spokesman, J.D. Nelson, told reporters that Petrov had three felony warrants and a misdemeanor warrant at the time of the encounter. 
 
 The local ABC affiliate interviewed a witness to the arrest. 
 
 "I heard just loud smack, smack, smacks. I really thought they were gunshots 'cause they were super loud," Redop Rundgren said. 
 
 Rundgren's apartment is above where the incident occurred. The screams woke him up, he told ABC News 7. 
 
 "They kept screaming, 'Get on the ground," pushing him and beating him continuously, he said. 
 
 "He started trying to get up and crawl away while they were beating him. That's when I heard his screaming like, 'Stop, help me' or something of the sort," Rundgren recalled. 

 Alameda County deputies on paid leave following video of beating 
 
 Two Alameda County Sheriff’s deputies were placed on paid administrative leave following the release of a video showing the officers beating a suspect with batons following a 38-minute car chase from the East Bay to San Francisco. 
 
 Sheriff Gregory Ahern placed the deputies on leave Sunday, two days after launching an investigation into the Thursday incident, said Sgt. J.D. Nelson, a spokesman for the sheriff’s office. The deputies were not identified. 
 
 The beating was the culmination of a car chase from San Leandro to San Francisco’s Mission neighborhood, with the suspect taking off after the deputies approached the man, who was sitting in a stolen car at about 1:38 a.m., according to Nelson. 
 
 The suspect, Stanislav Petrov, 29, reportedly rammed the deputies’ cars, knocking one of the officers down before fleeing the scene. 
 
 The officers pursued Petrov into San Francisco, where he crashed the car and then ran. 
 
 Two Alameda County Sheriff deputies are shown beating a man on a street in San Francisco's Mission District in a video screen grab provided by the San Francisco Public Defender's Office. Two Alameda County Sheriff deputies are shown beating a man on a street in San Francisco's Mission District in a video screen grab provided by the San Francisco Public Defender's Office. Photo: Coutesy Of San Francsco Public D Photo: Coutesy Of San Francsco Public D Image 1 of / 1 Caption Close Alameda County deputies on paid leave following video of beating 1 / 1 Back to Gallery 
 
 In the video released by San Francisco Public Defender Jeff Adachi, one deputy tackled the suspect and punched him while he was on the ground. Both deputies then pulled batons and beat Petrov repeatedly as the man screamed for help. 
 
 According to Nelson, the deputies believed the suspect to be armed and possibly on drugs. A gun was later recovered. 
 
 Petrov was taken to San Francisco General Hospital, where he remained Sunday. His condition was not available. Previous reports indicating he had been released and booked into County Jail were not accurate, Nelson said. 
 
 Adachi contended the video shows excessive force. 
 
 “He didn’t pose any threat at that point, and they are clearly using excessive force and trying to seriously hurt him when he was on the ground and subdued,” he said Friday. “I don’t see any reason why he couldn’t be handcuffed and taken into custody.” 
 
 Staff writer Vivian Ho contributed to this report. 
 
 Jill Tucker is a San Francisco Chronicle staff writer. E-mail: jtucker@sfchronicle.com Twitter: @jilltucker 

 ALAMEDA COUNTY (KRON, BCN) — The Alameda County Sheriff’s Office has launched a formal investigation after a video was released Friday night showing what appears to be deputies beating a man with batons in the Mission District in San Francisco. 
 
 The video, released by the San Francisco Public Defender’s Office on Twitter around 5:30 p.m. Friday, shows two deputies striking a man on the ground repeatedly with batons after a pursuit. 
 
 In a subsequent tweet the public defender’s office describes the video as “shocking and brutal.” The caption on the 13-minute video states that it comes from surveillance cameras that record in 10-second increments with gaps in between, “So the beating was actually twice as long as what is shown.” 
 
 Alameda Co. deputies beating man in SF. Time-lapse camera, so beating lasts twice as long as it appears in footage https://t.co/HdfXDn96PY — SF Public Defender (@sfdefender) November 14, 2015 
 
 //platform.twitter.com/widgets.js 
 
 Alameda County sheriff’s Sgt. Ray Kelly said Friday evening that the department had been alerted to the video shortly after it was posted online and had immediately started an internal affairs investigation into the incident. 
 
 “We’re going to do a complete and thorough investigation into this incident and figure it out,” Kelly said. Kelly said the capture and arrest shown in the video occurred early Thursday morning after a pursuit that started in San Leandro around 1:30 a.m. 
 
 Deputies had been patrolling a hotel parking lot in the 17200 block of Foothill Boulevard in San Leandro when they spotted a stolen 2015 Mercedes C300 sedan, Kelly said. 
 
 When they approached the vehicle, the suspect inside started the car, ignored orders to stop and allegedly rammed two police cars, injuring one deputy and disabling his patrol vehicle, Kelly said. 
 
 The suspect then led deputies on a chase on Interstate Highway 580 into Oakland and then west toward San Francisco, crossing the Bay Bridge at speeds of more than 100 miles per hour, Kelly said. He exited the freeway in San Francisco, struck a parked car on a city street and fled on foot before his capture, which was captured on the video seen. 
 
 Deputies detained Stanislav Petrov, who was taken to San Francisco General Hospital for treatment. 
 
 WARNING: THE BELOW VIDEO MIGHT BE DISTURBING TO SOME VIEWERS
– Two Alameda County sheriff's deputies who chased a suspect to San Francisco—and allegedly beat him to a pulp once they caught up with him—have been suspended while the incident is investigated. In video released by the San Francisco public defender’s office, which calls the video "extremely disturbing," the two officers can be seen chasing the man on foot and hitting him with their batons after he was brought to the ground, the San Francisco Chronicle reports. They can be seen hitting the man more than 30 times before other officers arrive—and the public defender's office says that since the footage was taken from security cameras with 10-second lapses, the beating lasts twice as long as it seems in the footage, in which the man can be heard begging for help, KRON4 reports. The suspect, who was hospitalized after his arrest, has been identified as Stanislav Petrov, an alleged car thief accused of ramming patrol cars before leading officers on a high-speed chase early Thursday morning, the Chronicle reports. Police say he took off on foot after crashing the car. Critics have accused the officers of using excessive force and likened the footage to the Rodney King video, the Los Angeles Times reports. "I was shocked by the brutality," a spokeswoman for the public defender's office tells the Times. "He is clearly not resisting. And they hit him multiple times in the head with their batons. It doesnt look like they're trying to subdue him. It looks like they're trying to punish him or trying to exact revenge." (Three Tuscaloosa cops were suspended after video of them dealing roughly with partying students emerged.)