UPDATE 11:46 p.m. CDT: Police confirm three people have been rescued from the water and their cars after the bridge collapse. There were no fatalities.
MOUNT VERNON, WASHINGTON (Reuters) - Part of a four-lane freeway bridge over a river in a rural area north of Seattle collapsed on Thursday, sending vehicles and people into the frigid water below, authorities said.
The collapse on Interstate 5 over the Skagit River happened at about 7 p.m. local time between the towns of Mount Vernon and Burlington, 55 miles north of Seattle, Washington State Patrol spokesman Trooper Mark Francis said.
"I've got reports of vehicles and people in the water," Francis said. He added that he did not know if anyone was injured.
Witnesses told KING-TV that a truck struck the bridge right before it collapsed. There's no confirmation yet, but authorities do say an inspector is looking into the possibility that a truck with an oversize load made contact with the structure.
The Seattle Times newspaper reported that three people were rescued from the water. Reuters was not able to immediately confirm the rescues with the Skagit County Sheriff's Office.
The cause of the collapse was not immediately known. It was not raining in the area, Francis said.
The bridge was built in 1955, according to the website for the privately run National Bridge Inventory Database. The highway and bridge are the main corridor for car traffic between Seattle and Vancouver, Canada.
The Skagit County Sheriff's Office, in a statement on its Facebook page, asked people to avoid the area to make room for emergency responders.
"Please try to stay off land and cell phones as the volume of calls has overloaded the system and first responders are not able to make needed calls due to line overload," the statement advised residents.
The collapse comes nearly six years after another bridge fell in Minnesota and raised concerns about faulty infrastructure in the United States.
In August 2007, about 1,000 feet of the I-35W bridge in Minneapolis collapsed into the Mississippi River during the evening rush hour. Vehicles plummeted into the water, killing 13 people and injuring another 145.
In a subsequent probe of the fatal collapse, the U.S. National Transportation Safety Board found more than a dozen steel support plates suspected of causing the disaster were deficient in size, and a routine inspection would not have uncovered the problem.