Seven passengers were taken to hospitals on Monday, one by helicopter, after Amtrak's "Vermonter," headed for Washington, hit "big hunks of ledge" that had fallen atop newly rebuilt tracks outside Montpelier, Vermont Gov. Peter Shumlin said.

Shumlin said speed was not an issue in the crash. Although state officials had not yet spoken to the train's engineer, the governor said, there was no reason to think anyone was negligent.

"There's no belief that there's any wrongdoing here," Shumlin said. He noted that a freight train had passed through the same section of track with no problems on Sunday night. He called the subsequent rock slide and crash "an act of nature, really beyond the control of anyone conducting the train or running the train or maintaining the track," which had been rebuilt using federal stimulus funds.

The National Transportation Safety Board is investigating.

The locomotive and a passenger car slid down an embankment toward a brook, leaking diesel fuel into the water, and several other cars also left the tracks, leaving senior citizens and passengers from as far as California scurrying for safety, terrified but alive, Shumlin said. "We're just grateful there was no loss of life," he added.

The four injured passengers and two injured crew members were treated and released on Monday, officials said, but one crew member remained hospitalized with serious injuries.

Cranes were being brought in to lift out the cars, and workers will rebuild a destroyed section of track. The Vermonter will continue north and south of the crash site, and buses will bridge that gap for passengers for an unknown length of time, Shumlin said.

Amtrak Train 55 derailed about 10:30 a.m. as it rounded a curve just south of a high trestle bridge that carries the rail line above Vermont Highway 12A, one of the state's larger north-south roadways. That section of railway is owned by the New England Central Railroad.

Passenger Ian Trupin, who was on his way south to New Jersey, said on Instagram that he was fine but shaken. He posted a photo taken from inside a train car showing a second car resting amid the trees down a steep embankment. A second Trupin photo showed a train car atop a section of track largely covered by jagged rocks.

Amtrak said the train, with 98 passengers and four crew members, was headed from St. Albans, Vermont, to Washington's Union Station. Shumlin said the area near the crash site in Northfield has a 59-mph speed limit.

Some U.S. tracks have fences to catch falling rocks and signaling systems to alert for slides, safety advocates said.

Shumlin said that cracked and falling rock ledges cause problems on state highways and that a tremendous effort is put into trying to prevent dangerous slides there. "We should be doing the same on our rail tracks," he said.

Seeming to try to deflect any Amtrak-related political sniping, which can follow such incidents, the governor noted that after car crashes "we don't say, 'Let's stop driving cars,' " but instead seek to improve safety.

"Rail's important as we fight climate change. Let's not throw out the baby with the bathwater as we face this tragedy," he said.