MOUNT VERNON, Wash.

- An interstate bridge over a river north of Seattle collapsed last night, 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.

The bridge is not considered structurally deficient but is listed as "functionally obsolete" - meaning that its design is outdated, according to a database compiled by the Federal Highway Administration. The bridge was built in 1955 and has a sufficiency rating of 57.4 out of 100, according to records.

- The Associated Press