The engineer who was involved in Sunday's New York train derailment apparently "was nodding off and caught himself too late" before the accident that killed four people and injured 67 others, a union representative who has been meeting with the man told CNN on Tuesday. 

Anthony Bottalico, the union representative, said engineer William Rockefeller Jr. recognizes his responsibility in the incident. 

"I think most people are leaning towards human error," Bottalico said. 

Rockefeller's lawyer, Jeffrey Chartier, characterized what happened as "highway hypnosis." He said his client had had a full night's sleep before the crash, and that Rockefeller had no disciplinary record. 

In a brief conversation with investigators, Rockefeller said that moments before the derailment of the Hudson Line train in the Bronx he was "going along and I'm in a daze. I don't know what happened," according to a law enforcement official familiar with that conversation. 

Asked by investigators what he was thinking when he said he was dazed, the engineer said he couldn't say. Rockefeller spoke to Metropolitan Transportation Authority and New York Police detectives at the crash site before he was taken to the hospital Sunday. 

National Transportation Safety Board member Earl Weener told a news conference that Rockefeller would have had a chance to get the necessary sleep prior to his 5 a.m. shift the day of Sunday's accident, echoing comment from Rockefeller's lawyer. 

According to NTSB representatives, results from alcohol breath tests for the train engineer were negative, and both the brake and signal systems in the deadly Metro-North accident appeared to be working. Other toxicology results have not yet come back. 
was anyone killed?
killed four people