A coal train that derailed in Maryland was going the authorized speed of 25 miles per hour with an engineer-in-training at the controls before the accident that killed two young women, a federal investigator said Wednesday.

Investigators were checking videos, track conditions and maintenance records to learn whether the college students sitting on a railroad bridge over the town's main street contributed to the Monday night crash or if their presence was just a tragic coincidence.

National Transportation Safety Board investigator Jim Southworth wouldn't speculate on the cause of the derailment.

"This is just not the time for any kind of analysis," he said Wednesday. "This is purely fact-finding."

So far, Howard County police have said that the two 19-year-old women were sitting on one side of the bridge with their backs to the tracks as the train passed a few feet behind them; their bodies were found buried under coal dumped from the train cars.

Investigators have also said the train's emergency brakes were applied automatically _ not by the three-man crew _ around midnight Monday, but they don't know why part of the train jumped the tracks.

Southworth said the train's two locomotives did not derail and that the crew reported they "felt nothing, and they saw nothing before emergency braking occurred on their train." Investigators planned to remove the tracks from the crash site and reassemble them in a nearby parking lot for inspection.

This is at least the third derailment involving a CSX train in Maryland this month, though the two others did not involve fatalities. Cumberland police reported a three-car derailment on another train in Cumberland the same night as the Ellicott City wreck. The other was in Woodstock Aug. 8, according to Howard County authorities.

Paul Bodnar, a rail safety consultant and former federal railroad investigator who is not involved in the investigation, said there are a number of potential causes for the derailment. He said a broken rail, a gap or buckle in the track, and a broken wheel could all be possibilities, given photos that show the first cars of the train derailed. Bodnar said it was also possible that the train's locomotives hit a weak spot on the track, causing a crack in the rail and derailing the following cars.

Bodnar said it was almost certain that a derailment caused the engagement of the train's emergency breaking system, not the other way around.

Cleanup of area, meanwhile, continued Wednesday. Nineteen of the 21 derailed cars had been removed. Howard County Executive Ken Ulman said he believes the NTSB is making progress toward reopening downtown and the work could be wrapped up in the next 48 hours.

Authorities also planned autopsies of the two women to determine how they died, and their bodies have been turned over to the state medical examiner's office.

The victims were Elizabeth Nass, a student at James Madison University in Virginia and Rose Mayr, a nursing student at the University of Delaware. Both were graduates of Mt. Hebron High School in Ellicott City, where they were on the dance team, and planned to finish college in 2014, according to friends and their Facebook pages.

Funeral services were scheduled for Friday and Saturday.

Tweets and photos from the women chronicled some of their final moments together as they enjoyed a summer night together before they headed back to school. "Drinking on top of the Ellicott City sign," read one tweet. "Looking down on old ec," read another.

The bridge the women were on is easily accessible from the picturesque downtown of Ellicott City, which is about 15 miles west of Baltimore, and generations of young people have played and partied along the tracks.

An original stone bridge was built around 1830, according to Courtney Wilson, executive director of the Baltimore & Ohio Railroad Museum in Baltimore. He said it was replaced after an 1868 flood with an iron truss bridge that provided wider lanes for vehicles passing beneath. That structure was replaced around 1930 with the current steel span.

Shelley Wygant of the Howard County Historical Society said the edge of the bridge on which the women sat, facing the Patapsco River, is at least 2 feet from the single set of railroad tracks. The side of the bridge facing the town has a wider platform, she said.

"I don't think anybody would want to be up there when trains go by," Wygant said, adding she had been on the span to hang banners and remembers thinking, "I hope a train doesn't come."

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Gresko reported from Washington. Associated Press writers David Dishneau in Hagerstown, Md., and Karen Mahabir in Washington contributed to this report.