The victim, named locally as Aqib Mazhar - who was in his 20s - was stabbed in the back after being targeted by the gang, said the woman.
They left him outside her home in Nottingham on Wednesday evening.
She tried to help Mr Mazhar but said his blood went "all over the pavement" as she turned him over.
Nottinghamshire Police said he died in hospital.
Updates on this story and more from Nottinghamshire
The witness said: "They were throwing bricks, they had poles."
"They were smashing the car window and this guy jumped into the back seat because they had smashed his side window, and as he jumped into the back the guy opened the door and [put a] knife into his back and he collapsed out on our driveway.
"The guy who was in the car with him ran off up the road and shouted to us 'Call an ambulance' and just left him on his own on our driveway to die."
She said there were several young men in three cars, which all stopped outside her house.
"They were just trying to smash the car but I was just thinking drive off, you know, lock your doors, and you're safe there," she said.
She dialled 999 and went outside to try to help Mr Mazhar.
"As I turned him onto his side all the blood just [went] all over the pavement," she said.
Police, who were called to Russell Road in Forest Fields at 20:35 BST on Wednesday, believe his fatal injuries were caused by a knife.
Another witness who lives in the road said she watched police doing first aid as they tried to save Mr Mazhar's life.
"I just heard a bang and I thought it was two cars crashed or something," she said.
"When I went to look out the window everything was going on.
"I wasn't surprised [he died] because I saw the police doing CPR on him and they didn't wait for the ambulance to come so it must have been serious."
The Jamia Masjid Sultania mosque in Sneinton wrote in a tribute on its Facebook page: "Please remember young brother Aqib Mazhar in your duas.
"He sadly passed away in the evening."
Officers are keen for anyone who witnessed what happened to come forward.

Border Force officers searched a trailer at Immingham Docks which had arrived from the Netherlands on Thursday night.
They found 8,960,000 cigarettes inside 20 wooden pallets.
If undetected, the Border Force estimated the haul would have cost the Treasury Â£2.5m in unpaid duty and VAT.
A gang of men armed with bricks and poles smashed their way into a man's car before leaving him dying on a driveway, according to a witness.
[NEXT_CONCEPT]
Almost nine million cigarettes hidden inside packages labelled as containing wooden flooring have been seized at a port on the River Humber.