BRIDGEPORT -- After a day of combing through the wreckage of two trains that collided during Friday evening's rush hour, federal investigators have found a broken rail, but they do not know if it was a factor in the eastbound train's derailment.

Federal investigators combed through Metro-North train wreckage Saturday in what promises to be a lengthy investigation into the cause of Friday night's rush-hour collision.

National Transportation Safety Board staffers pulled up in a caravan of cars along Commerce Avenue, joining an awaiting group of state and city officials for a mid-morning tour of the crash scene.

NTSB member Earl Weener told reporters the probe is focusing on the train's brake performance, condition of wheels, condition of tracks and signals.

"We'll also be looking at how the crew behaved (and) operated the train," Weener said.

He said data recorders should have been on board both trains, collecting their rate of speed and other information.

The goal is not only to determine what happened, he said, but seek to prevent it in the future.

The NTSB's working theory is that a Metro-North train heading east from New York City's Grand Central Terminal to New Haven derailed at about 6:10 p.m. just outside Bridgeport and was struck by a westbound train from New Haven to Grand Central on an adjacent track. About 700 were on board, 70 were taken to the hospital with two in critical condition.

The site of the wreckage is, essentially, being treated like a crime scene, with the media and curious onlookers kept at a distance while NTSB experts begin sifting through the debris for answers.

Weener said Day 1 is focused on time-sensitive, "perishable evidence."

That is going to be a daunting task, based on the descriptions from the elected officials who viewed the wreckage.

"The scene down there is enormously violent," said U.S. Rep. Jim Himes.

U.S. Sen. Richard Blumenthal said it looked like giant toys had been strewn throughout the area.

"The sides of cars are torn away like ribbons of cloth," Blumenthal said.

Weener added, "The tracks are very much torn up."

Asked about possible foul play, Weener said nothing could be ruled out at this stage.

With the Metro North line out of service between Bridgeport and Norwalk, Gov. Dannel Malloy and other lawmakers urged commuters to be patient. Malloy said as of mid-Saturday morning he could not provide good information on when train service would return to normal.

"We will set up a system to move people from Bridgeport to the next closest station that can handle that traffic," he said, adding right now that is South Norwalk. "Folks east of Bridgeport, you should being making plans for alternative travel."

Malloy said the city and state are trying to stay out of the NTSB's way.

"People will have to be patient," said U.S. Senator Chris Murphy. "We want to get this investigation right."

The elected officials also said it was fortunate there were not more injuries considering the scale of the destruction.

"It's frankly amazing there weren't more serious injuries and lives lost on scene," Murphy said.

The crash occurred right behind Steve Junker's car customizing shop, Sunlimited, on Commerce Drive just below the I-95 overpass.

It was mostly business as usual for Junker as Saturday's investigation continued. He did allow some media onto his property to take photos of the trains.

"We heard a big boom" Junker recalled from night before.

But he said he and his staff were used to the noise because of ongoing construction in the vicinity of the train bridge where Commerce Drive meets Fairfield Avenue.

"They're doing construction, pounding beams into the ground. All day long all you hear is, `Boom, boom, boom.' We assumed it was the grand finale," Junker said.

Curious onlookers made their way down to the accident site Saturday morning to see the wreckage in person.

"This is just unbelievable," said Steve Traski, a Wilton resident, as he aimed his camera at the train.

Traski grew up in Bridgeport.

Traski recalled playing as a child in a vacant lot at the corner of Commerce Drive and Fairfield Avenue, now home to a McDonald's.

"We used to play in there where the trains came by," he said.; 203-414-0712;