EMBED >More News Videos Video shows a police officer and a skateboarder colliding on Dolores Street Tuesday night during an informal skateboarding competition that drew hundreds of people to the Dolores Park.

Skateboarders and RIOT police. An only in #sanfrancisco moment. From what I've heard the police are allowing them to take the street. pic.twitter.com/bQsOh5RCDh — DB (@BoyerDina) July 12, 2017

Things turned ugly when officers in riot gear responded to a large gathering of skaters. It happened at Dolores Park and impacted traffic within a one-block radius of the park.Just after 7 p.m. units tried breaking up a large crowd and say people started throwing things at officers. Two cruisers were vandalized.One officer was injured and taken to the hospital.Officers tried to block skaters on the street with their patrol cars. One person tried to skate around them and flipped over. At one point officers let the crowd continue to skate.At least one skater was also rushed to the hospital. Local artist Matt "Milanoart" shared video of what he says is Jake Phelps, editor of "Thrasher" magazine taking a nasty spill.The whole scene ended about two hours after police arrived.