The National Transportation Safety Board says it is analyzing data recorders taken from a commuter train that derailed in New York City Sunday morning to determine whether excessive speed, mechanical problems or human error played a role in the deadly accident.

The derailment, near the Spuyten Duyvil station in the Bronx on Metro-North's Hudson Line, caused the train's locomotive and some of its seven cars to topple over and left the lead car inches from the water. Four people died and at least 60 others were injured, according to authorities. The station is located at a sharp bend where the Hudson and Harlem rivers meet.

Earl Weener, an NTSB member, said Monday morning that a second event recorder was found in the train's front car and has been sent to Washington for analysis. The other event recorder was found earlier in the rear locomotive.

Weener said investigators hope to download information from the memory cards from that recorder on Monday. They hope it can provide information on the speed of the train, how the brakes were applied and the throttle setting.

He told The Associated Press they've already had some success in retrieving data. But the information has to be validated before it's made public. The NTSB has said it could take as many as 10 days to investigate the accident.

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Investigators plan to conduct interviews Monday or Tuesday with the engineer and conductor, Weener said. He also said clues could be found from a signaling system operated by dispatchers at a central location.

New York State Gov. Andrew Cuomo said Monday on NBC's "Today" show that he thinks speed will turn out to be a factor.

"It was actually much worse than it looked," Cuomo said. "As the cars were skidding across the ground, they were actually picking up a lot of debris, a lot of dirt and stones and tree limbs were going through the cars so it actually looked worse up close," he said, calling it "your worst nightmare."

The New York Post identified the operator of the train as William Rockefeller, of Rockland County, N.Y. Citing law enforcement sources, the paper reported that Rockefeller insisted to investigators that he had tried to hit the brakes going into the Spuyten Duyvil bend, but they didn't work. The sources also described Rockefeller as a 20-year veteran of the MTA with a clean disciplinary record.

One of Rockefeller's neighbors, 52-year-old Tracy Pool, said Rockefeller was an avid motorcyclist who liked to "live on the edge."

“I wouldn’t say he’s such a speed demon," Pool said. "But he always stayed within the speed limit with his trains.”

The speed limit on the curve is 30 mph, compared with 70 mph in the area approaching it, Weener said.

One passenger, Frank Tatulli, told WABC-TV that the train appeared to be going "a lot faster" than usual as it approached the sharp curve near the Spuyten Duyvil station.

New York's Metropolitan Transportation Authority (MTA), which oversees Metro-North, warned commuters to expect crowded and delayed trains on Monday. It said that Hudson Line service would operate on a limited basis between Poughkeepsie and Yonkers, and shuttle buses would take commuters heading farther south to the 242nd St. subway station. Northbound travelers were told to take the subway to 242nd St., where the shuttle bus would take them to Yonkers. Passengers were urged to take the Harlem and New Haven lines into Grand Central Station, as the MTA said that Hudson line tickets would be honored on those lines.

Aaron Donovan, a Metro-North spokesman, said no major delays were reported during the early part of the rush hour.

"We'd like to get service up toward the end of the week," Cuomo said.

The MTA Police Department identified the deceased Sunday as Ahn Kisook, 35, of Queens, N.Y.; Donna L. Smith, 54, of Newburgh, N.Y.; James G. Lovell, 58, of Cold Spring, N.Y. and James M. Ferrari, 59, of Montrose, N.Y. Three of the dead were found outside the train, and one was found inside, authorities said. Autopsies were scheduled for Monday, the New York City medical examiner's office said.

Lovell, an audio technician for NBC's "Today" program, was traveling from his Cold Spring home to midtown Manhattan to work on the famed Rockefeller Center Christmas tree, said longtime friend Janet Barton. The tree-lighting ceremony is Wednesday night.

As of late Monday morning, 25 victims remained in area hospitals, with three in critical condition.

New York City Mayor Michael Bloomberg said after visiting an area hospital Sunday evening that none of the victims in critical condition appeared to have life-threatening injuries.

In their efforts to find passengers, rescuers shattered windows, searched nearby woods and waters and used pneumatic jacks and air bags to peer under wreckage.

Passengers were removed from the wreck by authorities, with dozens bloodied and scratched, holding ice packs to their heads.

"I was asleep and I woke up when the car started rolling several times,” said a bloodied Joel Zaritsky, who was on his way to New York City for a dental convention.

“Then I saw the gravel coming at me, and I heard people screaming. There was smoke everywhere and debris. People were thrown to the other side of the train."

About 150 people were on board when the train derailed, and Donovan said the railroad believed everyone aboard has been accounted for.

The derailment occurred near the Harlem River, and authorities say two cars were left lying on their sides, although none of the cars went into the nearby waterway.

“One approached the water and came close, but did not go in,” Donovan told FoxNews.com. He said a locomotive was pushing the train from behind, although the operating engineer who controlled the train was stationed in the front of the first passenger car.

Workers have started the arduous task of righting the toppled rail cars. Five passenger cars and the locomotive were back on the tracks by around 9:30 a.m.

“It’s going to be a long time before this is cleared up,” MTA spokeswoman Marjorie Anders told Fox News.

Donovan said the train was an express and was not due to stop in the Spuyten Duyvil station. Sunday’s incident occurred just south of where a train ferrying garbage derailed in mid-July.

The accident was the latest mishap in a troubled year for Metro-North, which had never before experienced a passenger death during an accident in its 31-year history.

It came six months after an eastbound train derailed in Bridgeport, Conn., and was struck by a westbound train. That crash injured 73 passengers, two engineers and a conductor.

For decades, the NTSB has been urging railroads to install technology that can stop derailing caused by excessive speed, along with other problems.

A rail-safety law passed by Congress in 2008 gave commuter and freight railroads until the end of 2015 to install the systems, known as positive train control. PTC is aimed at preventing human error — the cause of about 40 percent of train accidents. But the systems are expensive and complicated. Railroads are trying to push back the installation deadline another five to seven years.

Metro-North is in the process of installing the technology. It now has what's called an "automatic train control" signal system, which automatically applies the brakes if an engineer fails to respond to an alert that indicates excessive speed.

Such systems can slow trains in some circumstances but not bring them to a halt, said Grady Cothen, a former Federal Railroad Administration safety official.

The Associated Press contributed to this report.