A bridge over the Skagit River at Mount Vernon, Washington state, collapsed early today, hurling vehicles and people into the water.
Trooper Mark Francis of the Washington State Patrol said the four-lane Interstate 5 bridge collapsed at about 7pm local time.
He said he did not know how many people were in the water whether there were any injuries or deaths, or what caused the collapse.
A Skagit Valley Herald reporter at the scene said a sheriff's office rescue boat had arrived and rescue crews were looking for people in the water.
The reporter saw one person sitting on top of one vehicle in the water and a second vehicle in the water.
The collapse comes at the start of one of the country's busiest holiday weekends of the year.
The highway is the main one linking Seattle and Vancouver with other cities up and down the US Northwest.