Federal Investigators Will Interview Truck Driver Who Crossed Bridge Just Before Collapse

May 25, 2013— -- The trucker whose oversized load bumped the steel framework of a Washington State bridge just before it collapsed will be interviewed today by investigators from the National Transportation Safety Board, who are on the scene working to determine the cause of the collapse.

Three people were sent to the hospital with non-life threatening injuries after a portion of an Interstate 5 highway bridge in Mount Vernon, Wash., buckled Thursday, dumping two vehicles and a travel trailer into the icy water of the Skagit River, authorities said.

WATCH: Bridge Collapse Sends Cars, People Into Water

The semi truck was traveling in the right lane of the four-lane bridge when it is believed to have hit a girder just before the collapse, according to John Batiste, Chief of the Washington State Patrol.

The driver of the truck, who was identified as William Scott by The Associated Press, remained on the scene and has been cooperative, authorities said.

"I spoke to him seconds after it happened. He was just horrified," Cynthia Scott, the trucker's wife, told the AP.

"He gets safety awards, safety bonuses ... for doing all these checks, for hiring the right pilot cars and pole cars," she said.

Investigators were also trying to determine today how to pull the steel pieces of the bridge from the river and preserve them for analysis of what caused the bridge to collapse.

More than 77,000 cars cross the bridge daily and Lynn Peterson, Washington State's Secretary of Transportation, said officials were waiting on an assessment of the scene before determining whether an emergency bridge could be put in place.

Washington Gov. Jay Inslee told reporters Friday that one in five bridges in Washington have a rating of "functional obsolescence," which he described as "troubling." Inslee acknowledged the bridge collapse is going to cause a headache for tens of thousands of drivers.

"This is the aorta, the arterial of commerce for western Washington and we will ask all Washingtonians to help us avoid traffic problems," he said.

I-5 is the longest interstate highway on the West Coast, running from the Mexican border all the way north to Canada.

The bridge, built in 1955, was not considered structurally deficient but was listed as "functionally obsolete" -- a category indicating an outdated design, such as having narrow shoulders and low clearance underneath, according to a database compiled by the Federal Highway Administration.

Federal records show it had a sufficiency rating of 57 out of 100, meaning it was in need of repairs. The bridge was inspected twice last year, most recently in November, and repairs were made, Peterson said.

Victims Were En Route to Camp Ground

Dan Sligh and his wife, Sally, were among the injured transported to Skagit Valley Hospital in Mount Vernon. Sligh told ABC News affiliate KOMO-TV in Seattle that he was treated for cuts, bruises and a separated shoulder.

Sligh was driving his truck with a travel trailer attached to it to begin a camping trip. Sligh said he was crossing the bridge behind the semi-truck when the accident occurred around 7 p.m. local time.

"I was commenting to my wife that it seemed that the load he was carrying was about 4 feet wider than the actual bridge," he said.

The vehicles plunged about 40 feet from the bridge into the river, which set off a massive rescue operation.

"It was just a white flash and cold water," Sligh said. "The Skagit is quite cold this time of year."

Sligh said he acted quickly to rescue his wife, who was unresponsive after the collapse.

"Popped my shoulder back in so I could unbuckle everything so I could get over to her. Unbuckled her and pulled her into my side, which had less water," he said.

Helicopter footage from KOMO-TV showed several rescue boats in the river with several ambulances waiting on the shore.

"When you're sitting down in the water and there's all that mangled metal and bridge and you're looking around kind of pinching yourself and realizing you're lucky to be alive ... it's a pretty amazing day to tell you the truth," Sligh said.

ABC News' Rebecca Lee, Ben Gittleson, Michael S. James, Leezel Tanglao and David Kerley contributed to this story.