The accident quickly rippled throughout the system, causing long delays on a number of lines, with some commuters reporting being stranded on subway cars underground for more than an hour.
MTA officials said the train's emergency brake was activated before the crash, but the cause is still under investigation. A subway train derailed near a station in Harlem on Tuesday, frightening passengers and resulting in a power outage as people were evacuated from trains along the subway line. Passengers interviewed by local TV stations described the train vibrating wildly and bucking as it went off the rails.
The incident was reported just before 10 a.m., authorities said.
In the aftermath, transit workers will inspect "every inch of rail" to make sure all the equipment that's stored in the subway system is properly secured, officials said.
The derailed train was evacuated, along with two other trains - one ahead of it and one behind it.
Julian Robinson said he was stuck on one stopped train for 45 minutes to an hour before rescuers arrived to escort passengers along the tracks into the station.
Fire officials said 34 people suffered non-life-threatening injuries. The derailment tossed people to the floor and forced hundreds of passengers to evacuate through darkened tunnels. "I don't think anyone was hurt".
Transit officials say a preliminary investigation shows that the derailment was caused by an improperly secured piece of replacement rail that was on the tracks.
It is "under investigation", said the company MTA, which manages transit in NY city. The smoke was caused by sparks and the garbage and sanitation along the subway tracks.
During an interview last month on CNBC, the Democratic governor said the federal government was to blame for not responding to the state's requests for transportation funding, leaving NY "way behind" on infrastructure.
The governor of the State of NY, democrat Andrew Cuomo, who is in charge of the MTA, has promised to tackle the structural reasons for why delays and incidents seem to accumulate, leading to an increasing number of complaints from users.