By David Gaffen and Curtis Skinner
NEW YORK, Dec 2 (Reuters) - Commuters from New York City's northern suburbs faced travel delays on Monday morning, the day after a seven-car train derailment killed four people and injured 11 critically.
A portion of a Metro-North Railroad line between the Bronx and part of Westchester County could be closed for a week or more after the accident on Sunday, in which a Manhattan-bound commuter train ran off the tracks while rounding a sharp curve in the Bronx.
It was the latest in a string of problems to affect the railroad, including a May derailment in Connecticut that injured more than 70 people.
Service was suspended on the railroad's Hudson line, which serves 26,000 commuters on an average weekday, between the village of Tarrytown and Manhattan's Grand Central Terminal, according to the state's Metropolitan Transportation Authority, the parent company of Metro-North.
The MTA was providing bus service as an alternative, and urged Westchester County residents to use its Harlem line.
A team from the National Transportation Safety Board arrived in New York City on Sunday and said its investigation would look at track conditions and the train's mechanical equipment. The board will also explore any link between Sunday's accident and a freight train derailment in the same vicinity in July.
New York Governor Andrew Cuomo said it is unclear how long it will take the NTSB to review the "black box" data recorder, recovered from the train.
"They haven't given us a timeframe," Cuomo told NBC's "Today" on Monday. New York officials hope to get rail service on the commuter line back up by week's end, he added.
"We want to get service restored," he said.
As for the root cause of the derailment, officials "haven't gotten anything specific from the NTSB," but it could have been a track problem, an equipment malfunction or operator error, Cuomo said.
Although the tracks at the site included a "tricky turn," Cuomo said, "It's not about the turn. I think it's going to turn out to be about the speed more than anything and the operator's operation of the train at that time."
NTSB officials said they planned to provide an update on their investigation later on Monday.
The crash happened about 100 yards (meters) north of Metro North's Spuyten Duyvil station in the Bronx, in a wooded area where the Hudson and Harlem rivers meet. One car was toppled near the water.
Monday morning commuters said they had come up with workarounds to avoid the closed line.
Lisa Schulman, a trade show producer who lives in Dobbs Ferry, had turned to bus service.
"I took the bus to the train, and I'll be dependent on the bus and the cabs," said Schulman, who had been on a Metro-North train that derailed earlier in the year.
Tarrytown resident Santa DeFeis, a 50-year-old legal secretary, said she'd had to add another 20 minutes to her commute to drive to another rail station on a different line not affected by the derailment.
"It's a big inconvenience," she said. "But it was a tragedy what happened. People lost their lives."
Metro-North also experienced an outage on its heavily traveled New Haven line in late September and early October after a power substation operated by Consolidated Edison Inc failed.