(Mount Vernon, WA) -- The Interstate 5 bridge collapse into the Skagit River was caused by an oversize truck hitting the span, the Washington State Patrol chief said.
"For reasons unknown at this point in time the semi struck the overhead of the bridge causing the collapse," Batiste told an overnight news conference.
The truck made it off the bridge and the driver remained at the scene and cooperated with investigators.
Two other vehicles went into the water Thursday evening as the structure crumbled. Three people were rescued and are recovering.