Victim of biker gang attack on SF highway IDd as ride share driver

Up to 15 men on dirt bikes and all-terrain vehicles were being sought by police Thursday after they surrounded a car on Highway 101 in San Francisco a day earlier and started vandalizing it, and then pummeled the driver to the ground when he got out apparently to confront them.

Natalie King, a 32-year-old resident of Modesto, identified the victim of Wednesday evening’s attack as her 35-year-old brother, Alex, who lives in Modesto but comes to San Francisco almost every day to drive for a ride share company.

“He’s a good guy. He’s not a troublemaker or nothing like that. I don’t understand why someone would beat him up,” said King, adding that Alex was a new father to a baby boy.

She asked not to disclose Alex’s full name.

A group of dirt bike riders appear to vandalize a car and assault a driver on southbound Hwy. 101 at the Cesar Chavez St. in San Francisco Wednesday, March 8, 2017. A group of dirt bike riders appear to vandalize a car and assault a driver on southbound Hwy. 101 at the Cesar Chavez St. in San Francisco Wednesday, March 8, 2017. Photo: Courtesy Video Photo: Courtesy Video Image 1 of / 5 Caption Close Victim of biker gang attack on SF highway IDd as ride share driver 1 / 5 Back to Gallery

The road rage incident occurred at the Cesar Chavez Street exit during the evening commute and was partly videoed by several witnesses, including one driving by in an Uber car.

“I saw the male bikers surround the vehicle and started to yell, break side mirrors and also physically hitting the vehicle. It seemed like they were provoking the driver to come out,” said the witness from the Uber, who shared video footage of the attack with The Chronicle.

The “driver came out of the car when the biker gang started beating him up,” said the witness, who asked to remain anonymous.

The brutal beat-down occurred just after 6 p.m. Wednesday in the southbound lanes of Highway 101 when a dark car drove in front of a white Toyota, stopping the driver as the group of bikers surrounded him.

A Chronicle reporter first spotted the group on Sixth and Mission streets in the South of Market neighborhood of San Francisco just before 6 p.m., reporting that they were standing on their seats and doing stunts in the middle of streets.

Before Alex exited his car, one of the bikers in a red sweatshirt began punching the rear side windows of the Toyota.

The video shows him falling to the ground and tumbling as one of the bikers stood over him and repeatedly punched him. The biker — wearing acid-wash jeans, white sneakers and a dark top — appears to move away from the man as another biker with his helmet on takes over, punching and kicking the driver as he struggles to get up and shield himself.

It was unclear how the fight started or ended.

Several witness called 911 to report the attack.

“I don’t know what was said to who or who said what,” Officer Vu Williams of the California Highway Patrol said of the incident.

He said witnesses told CHP officers the bikers were driving slowly prior to the incident and popping wheelies on the highway, causing a traffic backup across all lanes.

The motorcyclists fled before CHP officers arrived on scene, Williams said.

Alex was taken to San Francisco General Hospital with a broken leg and other non-life-threatening injuries. King said that since the incident, her brother had to go into surgery for a broken leg and has been “out of it” since.

“I’m at a loss,” said King, who was planning to drive to San Francisco Thursday evening to be with her brother.

Investigators are reviewing video footage of the incident and attempting to identify the 10 to 15 suspects involved, Williams said.

None of the bikes appeared to have license plates.

Roving biker groups flouting traffic laws have long been a problem in San Francisco. Numerous online videos show large groups of bikers, sometimes dressed in Santa Claus costumes, popping wheelies and doing burnouts on the Golden Gate Bridge and city streets.

There have been numerous biker incidents in the Hayes Valley neighborhood, said Officer Giselle Talkoff, a spokeswoman for the San Francisco Police Department.

“They’re biking up and down some stairs near some apartment complexes,” Talkoff said. “We won’t chase them because it’s too dangerous” for police and innocent bystanders.

The CHP asks for any witnesses of the incident to call them at (415) 557-1094 during business hours or call the CHP Golden Gate Communications Center at (415) 551-4100 outside of business hours.

Sarah Ravani and Kurtis Alexander are San Francisco Chronicle staff writers. Email: sravani@sfchronicle.com, kalexander@sfchronicle.com Twitter: @SarRavani, @Kurtisalexander