GOLDEN, Colo. -- Three people traveling inside a sport utility vehicle were killed Saturday morning when a massive steel girder fell onto the eastbound lanes of Interstate 70 at C-470.

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Governor Offers Condolences To Victims' Family

The man, woman and young girl inside a blue Dodge Durango were killed instantly when their vehicle was crushed by the 40-ton, 100-foot-long girder, 7NEWS reported.

All eastbound lanes on I-70 near C-470 were closed Saturday while the investigation is in progress, highway officials said.

The girder was put up Tuesday as crews were adding a lane to a bridge carrying C-470 over I-70, said state Department of Transportation spokeswoman Stacy Stegman. The beam was resting on concrete pillars at both ends, with the middle draped across all three lanes of the highway. The crushed remains of the car were underneath.

"This is about as bad as it gets," State Patrol Capt. Jim Wolfinbarger said.

Gov. Bill Owens visited the accident site and offered condolences to the family of the unidentified victims.

"I'd say I'm sorry. This is a horrible tragedy, one that you wouldn't want to have happen to anybody, and we're going to do everything we can to learn from it so it doesn't happen again," Owens said.

The girder was attached to the existing bridge with five braces spaced evenly along its length, and the girder collapsed after temporary braces gave way, Stegman said. Authorities had not determined why, she said.

"We have no reason to believe that this should have happened," said Stegman. "We are looking into it. It's very tragic."

U.S. Rep. Bob Beauprez said investigators were looking into the possibility of "criminal tampering." Jefferson County sheriff's spokesman Jim Shires confirmed deputies were investigating but added, "We are not suspecting criminal activity took place."

Investigators were said to be going over records of the contractor working on the bridge-widening project.

Asphalt Specialties Co. was overseeing the construction project and subcontractor Ridge Erection Co. put the girder in place, Stegman said. The governor said Asphalt Specialties was cooperating with state and federal investigators. The phone rang unanswered at the company's Colorado office on Saturday.

Asphalt Specialties is an experienced company with about six other highway projects currently underway in the state, Stegman said.

When it fell, the girder split the SUV in half, with the front driver section coming to rest several hundred yards in front of the back section.

Agencies from several jurisdictions rushed to the scene when the accident was first reported as a bridge collapse at around 10 a.m.

No cars were on the overpass at the time the girder fell because the bridge was under construction. Witnesses say a large crane was working in the area when they heard a large boom.

The accident backed up traffic on I-70 in both directions for miles. One westbound lane stayed open through the accident scene.

Eastbound traffic was being forced off at the Morrison exit. CDOT was advising drivers to use Highway 6 as an alternate route, connecting with U.S. 40 and then joining I-70 at the Morrison interchange. Traffic on C-470 was not affected by the accident.

Because the girder is so big, it may have to be cut apart for removal.

National Transportation Safety Board investigators were en route and were to meet with Jefferson County officials Sunday morning.