Accident investigators in the United States say a commuter train that derailed in New York City, killing four passengers, was travelling at more than twice the speed limit.
The investigators say the Metro-North Railroad train was travelling at 130km/h when it left the tracks on 1 December on a sharp bend in the borough of Bronx.
Four people were killed and 63 injured when the train derailed about 7.20am (local time) on a curve with a 50km/h speed limit.
Earl Weener from the National Transportation Safety Board said they were not aware of any problem with the brakes.
He said the train had made nine stops prior to the derailment, and officials had not yet uncovered any brake problems, the BBC reports.
Mr Weener said preliminary data from the train's event recorders indicated its brakes became fully engaged just five seconds before the locomotive came to a complete stop after the crash. In addition, he said the train's throttle went to idle six seconds before it came to a stop.
Authorities are continuing to question the train's engineer and three other crew members, and planned to transport the locomotive to a secure facility for further examination.
Officials are examining the engineer's mobile phone - a standard procedure, Mr Weener said.
The engineer and assistant conductor were both injured in the crash. Authorities also obtained surveillance video of the derailment from a nearby bridge but the picture was of low quality, he said.
