A high-speeding motorcyclist died Sunday night while trying to evade police during a string of sideshows that shut down down several parts of Oakland, officials said.
Portions of Interstate 580 and 880 also came to a standstill during the sideshows, authorities said.
"The sideshow did close down the entire freeway," CHP Officer Sean Wilkenfeld said. "The participants in essence did their own traffic break, stopped all traffic and began spinning donuts and popping wheelies."
About 150 cars and motorcycles participated in the sideshows. When officers arrived a motorcyclist suspected of participating in the event took off toward Castro Valley at 100 miles per hour with headlights off, according to the CHP.
Officers said the motorcyclists crashed into a SUV and died at the scene.
"I don't they go out that evening thinking that's what's going to happen," CHP Officer Eric Thomas said "But in the end when you're going to drive 100 mph with not lights or have ill regard for others, tragedies like this are going to happen.
Oakland police said there has been a recent increase in reckless sideshow activity and are teaming up with the CHP to produce a public safety announcement about the troubling trend.
Investigators are examining video posted on social media to try to identify those involved, but have not made any arrests as of Monday afternoon. Officials said many of the cars had license plates covered.
Police are asking for the public's help by providing license plate numbers and descriptions of vehicles.
"We're encouraging people to be good witnesses," Wilkenfeld said. "If you see a sideshow, obviously stay away from it and contact authorities."
Police said being a spectator to sideshows can land you a citation and possible jail time. In addition, sideshow participants may have their vehicle impounded for 30 days, police said.