A fatal New York City train derailment last year was likely caused by the engineer at the controls who fell asleep due to an undiagnosed sleep disorder, the U.S. National Transportation Safety Board said on Tuesday.
The Manhattan-bound commuter train was traveling more than 50 miles per hour (80 kph) faster than the speed limit when it rounded a curve and derailed shortly after 7 a.m. on Sunday, Dec. 1, 2013, the NTSB said in its findings.
Four people were killed and at least 61 people were injured in the derailment of the Metro-North Railroad train, it said.