MOUNT VERNON, Washington (AP) -- Authorities searched for a temporary span after a key bridge linking the U.S. and Canada collapsed, dumping a handful of vehicles and people into the icy water.
All three people who fell into the Skagit River in northwestern Washington state escaped with only minor injuries.
The four-lane Interstate 5 bridge collapsed about halfway between Seattle and Vancouver, British Columbia, after an oversize truck hit the span, the Washington State Patrol chief said.
Officials are trying to find out whether the spectacular collapse of a bridge on one of the West's most important roadways was a fluke _ or a sign of a bigger problem with thousands of bridges across the U.S.
Authorities focused first on trying to find a temporary span for the Skagit, although it won't come in time for the tens of thousands who would travel between Canada and Seattle during one of the busiest holidays in the U.S., Memorial Day weekend.
"You cannot overstate the importance of this corridor to Washington state," Gov. Jay Inslee said. Traffic on I-5 and surrounding roads was backed up for miles, a situation the governor said would continue indefinitely.
Officials were looking for a temporary, pre-fabricated bridge to replace the 160-foot (50-meter) section that failed, Inslee said Friday. If one is found, it could be in place in weeks. If not, it could be months before a replacement can be built, the governor said.
The trucker, William Scott, was hauling a load of drilling equipment when his load bumped against the steel framework over the bridge. He looked in his rearview mirror and watched in horror as the span collapsed into the water behind him.
"He looked in the mirrors and it just dropped out of sight," Cynthia Scott, the trucker's wife, said from the couple's home in Canada. "I spoke to him seconds after it happened. He was just horrified."
The truck driver works for Mullen Trucking in Alberta, the Washington State Patrol said. The tractor-trailer was hauling the equipment southbound when the top right front corner of the load struck several of the bridge's trusses, the patrol said.
Scott, 41, remained at the scene and cooperated with investigators. He voluntarily gave a blood sample for an alcohol test and was not arrested.
Scott has been driving truck for 20 years and hauling specialized loads for more than 10.
Initially, it wasn't clear if the bridge just gave way on its own. But Washington State Patrol Chief John Batiste blamed it on the too-tall load. The vertical clearance from the roadway to the beam is 14.6 feet (4.45 meters).
The truck made it off the bridge, but two other vehicles went into the water about 25 feet (7.6 meters) below as the structure crumbled.
Dan Sligh and his wife were in their pickup heading to a camping trip when he said the bridge before them disappeared in a "big puff of dust."
"I hit the brakes and we went off," Sligh told reporters from a hospital.
Bryce Kenning said the bridge seemed to explode in front of him. The 20-year-old slammed the brakes and could see the edge of the pavement approaching, but there was nothing he could do.
"It was like time was frozen _ like a roller coaster where you're not attached to the tracks," Kenning said in a phone interview.
Ed Scherbinski, vice president of Mullen Trucking, said in an interview with The Associated Press that state officials had approved of the company's plan to drive the oversize load along I-5 to Vancouver, Washington, and the company hired a local escort to help navigate the route.
Mike Allende, a state Department of Transportation spokesman, confirmed the truck had a permit.
State officials approved the trucking company to carry a load as high as 15 feet, 9 inches, according to the permit released by the state. However, the southbound vertical clearance on the Skagit River bridge is as little as 14 feet, 9 inches, state records show. The bridge's curved overhead girders are higher in the center of the bridge but sweep lower toward a driver's right side.
It's not rare for trucks to strike bridges in Washington state _ it's just that such accidents don't usually cause the structures to collapse.
The state transportation department said there were 21 bridge-strikes involving trucks last year, 24 in 2011 and 14 in 2010.
Officials performed a special inspection six months ago of the bridge that collapsed because there were indications it had been struck by a different vehicle.
A report released Friday says the checkup was done due to "impact damage," and inspectors identified tears, deformations and gouges on the northbound side of the bridge. The report also summarizes a variety of parts on the bridge that have been subjected to "high-load" hits.
State officials did not respond to a phone call seeking more detail.