An Interstate 5 bridge over a river north of Seattle collapsed Thursday evening, dumping vehicles and people into the water, the Washington State Patrol said.

The four-lane bridge over the Skagit River collapsed about 7 p.m., Trooper Mark Francis said. There was no immediate estimate of how many people were in the water or whether there were any injuries or deaths, he said.

It also was not known what caused the collapse of the bridge about 60 miles north of Seattle in Skagit County, which stretches from the North Cascades National Park to a cluster of islands off the Washington coast.

Xavier Grospe, 62, who lives near the river, said he could see three cars with what appeared to be one person per vehicle. The vehicles were sitting still in the water, partially submerged and partly above the waterline, and the apparent drivers were sitting either on top of the vehicles or on the edge of open windows.

“It doesn’t look like anybody’s in danger right now,” Grospe said.

Businesses in the area told a reporter that their power flickered about the time of the collapse.

Crowds of people lined the river to watch the scene unfold, The Skagit-Valley Herald reported. The newspaper said three rescue boats and several private vessels were attempting to help people in the water while crews on the road redirected traffic, which was backed up along area roads.

Washington state was given a C in the American Society of Civil Engineers’ 2013 infrastructure report card and a C- when it came to the state’s bridges. The group said more than a quarter of Washington’s 7,840 bridges are considered structurally deficient of functionally obsolete.