One person suffered from anxiety and another person reported a minor injury, but neither required medical treatment, Seaton said.
The derailment occurred 100 feet north of the stop at 57th Street and Seventh Avenue, Seaton said. One wheel on each of the two cars came off the tracks, according to a statement by NYC Transit late Sunday.
The train's 449 passengers were removed from the tunnel on a "rescue train," officials said.
"Something was wrong with the hand brake," passenger Mike Garelik said. "When they restarted it, it looks like it took one of the cars off the rail."
The cause of the derailment remains under investigation. Seaton said the train's operator and conductor would receive post-procedural, blood alcohol testing following an accident.
The cars were removed from the track to a Brooklyn rail yard on Sunday evening and crews were making repairs.
Some N train service remained suspended Sunday night and R trains were rerouted.
