PORTLAND, Ore. (AP) — The Fremont Bridge in Portland was closed for at least an hour Sunday as more than 100 people arrived at southbound Interstate 405 to watch what appeared to be a planned car stunt.

Hundreds of cars and trucks were at a standstill around 10:30 p.m. while other cars raced along the shoulder of southbound Interstate 405 to gather in the center of the bridge, The Oregonian/OregonLive reported.

A group of cars blocked traffic, performed stunts and lit fireworks.

Dozens of people jumped out of their cars and ran toward the chaotic scene, maneuvering between cars filled with people trying to get home that had been stuck in the mayhem. The event was called a “bridge takeover.”

Sergeant Kevin Allen, a public information officer for the Portland Police Bureau, said officers were aware of the takeover at Fremont Bridge, but that officers were responding to “high priority safety calls.”

Early Monday morning, officers did respond and disperse a street event where police issued one citation, Allen said.

Last week, Portland City Council passed an emergency ordinance to revise city code to make “street racing” or “sliding” misdemeanor offenses — labeling them, “Unlawful Street Takeover” and “Unlawful Staging of a Street Takeover Event.”