Was the engineer controlling the Metro-North train that derailed Sunday morning, killing four people, asleep when the accident happened?

Investigators believe so, according to a report on DNAinfo New York.

Four people were killed and more than 60 injured when the eight-car train derailed from the tracks just before 7:30 a.m. Sunday. Those who died, as identified by the MTA Police Department and reported by Fox News, are Ahn Kisook, 35, of Queens; Donna L. Smith, 54, of Newburgh; James G. Lovell, 58, of Cold Spring, N.Y. and James M. Ferrari, 59, of Montrose, N.Y.

DNAinfo New York reported that train engineer William Rockefeller, the man who was operating the controls of the train at the time, had dozed off minutes before the derailment and woken up as the train was headed into the curved section of the track. It was also reported that the train was traveling at a speed of 82 mph around the 30 mph curve.

Rockefeller, 46, has been a Metro-North employee for the past 20 years, according to DNAinfo New York, and an engineer for about 11 years.

New York Governor Andrew Cuomo told news anchors of “The Today Show” Monday morning that speed could have been a factor. Cuomo said the National Transportation Board is looking into whether the accident was the operator’s error, a problem with the track or an issue with the train.