The major highway bridge linking the US city of Seattle with Canada has collapsed, dumping at least a handful of vehicles and people into a river. Washington State Patrol said no one died, but three people were taken to hospitals. The four-lane Interstate 5 bridge - more than half a century old - collapsed on Thursday night about 7pm local time, halfway between Seattle and Vancouver, British Columbia, Trooper Mark Francis said. Bridge collapse: vehicles fell into the river. Francis said he did not know what caused the collapse, which came at the start of one of the busiest holiday weekends of the year. Kari Ranten, a spokeswoman for Skagit Valley Hospital, said two people who were injured in the collapse were en route to the facility. She said another person was being taken to a different area hospital. Xavier Grospe, who lives near the river, said he could see three partially submerged cars, and the apparent drivers sitting either on top of the vehicles or on the edge of open windows. Plunge: people sit on their vehicles in the river. Photo: @mdeyerin "It doesn't look like anybody's in danger right now," Grospe said. Helicopter footage aired by KOMO-TV in Seattle showed one rescue boat leaving the scene with a person strapped into a stretcher. A damaged red car and a damaged pick-up truck were visible in the water, which appeared so shallow it barely reached the top of the car's bonnet. A man told the local Skagit Valley Herald newspaper he felt a vibration and looked in his rear view mirror to see that the part of bridge he had just crossed was no longer behind him. "I thought something was wrong with my car at first," he said. The water in the Skagit River is believed to be about four degrees Celsius at this time of year. Bart Treece, from the Washington State Department of Transportation, told KBOI2 that he was unsure when the Skagit River Bridge, which is located between Burlington and Mount Vernon, was last inspected. It was built in 1955. "All of our bridges in the area are pretty old," he said. The bridge is not considered structurally deficient but is listed as being "functionally obsolete" - a category meaning that their design is outdated, such as having narrow shoulders and low clearance underneath, according to a database compiled by the Federal Highway Administration. The bridge has a sufficiency rating of 57.4 out of 100, according to federal records. That is well below the state-wide average rating of 80, according to an Associated Press analysis of federal data, but 759 bridges in the state have a lower sufficiency score. According to a 2012 Skagit County Public Works Department, 42 of the county's 108 bridges are 50 years or older. The document says eight of the bridges are more than 70 years old and two are over 80. 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 7840 bridges are considered structurally deficient or functionally obsolete. smh.com.au with AP