The engineer of the train that derailed on the weekend in The Bronx admitted to investigators that he was dozing off before the accident, in which four people lost their lives and more than 60 were injured, local media reported Tuesday.

William Rockefeller, 46, "admitted indirectly" to investigators that he was falling asleep before the train derailed as it rounded a sharp curve at almost three times the speed limit, sources close to the investigation said.

In his first remarks to the National Transportation and Safety Board, or NTSB, Rockefeller said that he had not consumed any alcohol, and now investigators are awaiting toxicology reports, the daily New York Post reported.

Reports are that the engineer, who apparently began his career as a custodian at Grand Central Station 20 years ago before qualifying to be a Metro-North engineer about 11 years ago, had run the same route often, but he had only been working the early morning shift for a couple of weeks.

He is said to have told investigators that he caught himself "nodding" just before the derailment and was alerted to the fact that the train was going too fast by a warning whistle, whereupon he hit the brake.

Among other things, NTSB experts are reviewing the engineer's schedule to determine if he had worked too much prior to the crash. Evidently, he had switched to the morning shift two weeks previously, the sources said.

Investigators have carried out a preliminary review of Rockefeller's cell phone and apparently have found no evidence that he was using it to make a phone call or to send text messages, The New York Times reported.

New York state Gov. Andrew Cuomo announced in the wake of the tragedy that he had ordered new precautionary measures to protect passengers, including obligating all Metropolitan Transport Authority employees to participate in discussions regarding safety.

The Metro-North commuter train was barreling along at 132 kph (82 mph) when it reached the 48-kph (30-mph) zone at 7:22 a.m. on Sunday, the NTSB's Earl Weener told a news conference on Monday.

When asked whether the crash was caused by faulty brakes or human error, he replied: "The answer is, at this point in time, we can't tell."

The throttle was cut six seconds before the locomotive skidded to a stop and the brakes were only applied at maximum pressure five seconds before the derailment, Weener said.

Investigators have not determined as yet whether the train had mechanical problems, given that it stopped at all the stations after leaving Poughkeepsie en route to Grand Central Station in the heart of Manhattan.

The technical details regarding the train's speed were extracted from the train's two black boxes, the NTSB official said. EFE