SAN FRANCISCO (CBS SF) — A confrontation with motorcyclists staging a sideshow on Highway 101 ended with a car being forced to stop during the evening commute and the driver assaulted — an attack that was captured on cell phone video.

The California Highway Patrol said the incident took place at 6:15 p.m. Wednesday on southbound Highway 101 near the Cesar Chavez exit in San Francisco.

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On the video, a group of motorcyclists are seen doing tricks and backing up commute traffic on the highway while staging a sideshow. A white sedan — driven by a 30-year-old Uber driver — then gets into a near collision with one of the motorcyclists.

The sedan and the group of about 10-15 motorcyclists continue on the highway a short distance until a black car stops in front of the white sedan, boxing it in and forcing it to stop near the exit.

The motorcyclists also stop and begin pounding on the sedan’s windows. At that point, the Lyft driver of the sedan gets out of the vehicle and is punched and kicked by one of the motorcyclists.

KPIX 5 spoke with the driver who took the video of the incident by phone.

“They started hitting his car and smashed his window and the either pulled him out or he got out of the car and about four or five of these guys took shots at him,” the driver explained.

The witness, who didn’t want to be identified, said his phone died as the beating began. Then he stopped to help the driver.

“He was in agony, he was crying out and he very clearly had a broken leg,” said the witness.

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The driver is recovering in the hospital. The motorcyclists fled the scene.

Witnesses to the incident were interviewed and a video the driver took showing the altercation was obtained and booked into evidence.

CHP officer Vu Williams said they’ve seen groups like this causing problems on roadways all over the Bay Area, but without license plates, they’re difficult to catch.

“They’re pretty mobile. They can go places a car cant necessarily go,” said Williams. “A lot of times to they have a real disregard for public safety, so they jump on the sidewalks and ride the wrong way.”

Often CHP have to rely on witnesses and video to make arrests. Many groups, like this one, post video on social media of themselves popping wheelies or riding down sidewalks.

Just over a year ago, a KPIX 5 investigation exposed a Marin County deputy as a member of one of those gangs, breaking the law on his bike when he was off the clock.

CHP officials said they don’t know if this is that same gang, but says all of them are a problem, especially when they escalate to violence.

The CHP says they’re hoping more witnesses will come forward so they have a better chance of identifying the bikers.

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At this time, the CHP San Francisco Area Office is asking for anyone who may have witnessed the incident to contact their office at 415-557-1094 Monday-Friday between 8 a.m. and 5 p.m. and ask for the Watch Officer. Outside of those hours witnesses can contact CHP Golden Gate Communications Center at 415-551-4100.