ARCADIA (CBSLA) — Hordes of onlookers descended on several Los Angeles-area neighborhoods Saturday night to view the potentially dangerous and ill-advised street takeovers.

The tire marks are still visible at the intersection of West Duarte Road and South Baldwin Avenue in Arcadia, where 300-400 people were reportedly gathered watching cars do burnouts, sometimes coming dangerously close to spectators.

“I was in shock,” Shawn Shawver told CBS2 News. He said at around 1 a.m. Sunday, he was at a nearby bar when he started hearing screaming and tires screeching.

“They blocked the intersection to do donuts, and it was, like, going off about eight to 10 minutes before you heard police sirens coming,” said Shawver, adding that the bar he was in went into lockdown mode as people tried to run away from police when they finally did arrive.

The quiet was short-lived, as another takeover materialized in Pico Rivera. This one turned rowdier as spectators threw rocks at police and aimed fireworks at them.

“It’s crazy. We have a very quiet neighborhood and nice neighborhood, and I don’t want to see this getting started,” one woman said.

It’s not clear whether it was related to Mexico’s World Cup win over South Korea Saturday morning, but cars could be seen with large Mexican flags waving during the burnouts.

Two people were arrested, but no injuries were reported.

In April, the California Highway Patrol said it would be creating a task force to begin cracking down on these so-called “sideshows.”