The Washington state I-5 bridge collapsed into Skagit River in the US on May 23, sparking a rescue operation with unconfirmed reports of people in the water. The four-lane bridge, halfway between Seattle and Vancouver, British Columbia, collapsed on Thursday night. [Photo/Xinhua]

MOUNT VERNON, Washington - The Washington State Patrol says a highway bridge over a river has collapsed, dumping vehicles and people into the water.

Trooper Mark Francis says the four-lane bridge collapsed about halfway between Seattle and Vancouver, British Columbia.

Francis says he has no idea how many people are in the water or whether there are any injuries or deaths.

He does not know what caused the collapse.