An underground smoke condition caused problems on several subway lines between Lower Manhattan and Downtown Brooklyn, the MTA said.
Riders had to be taken off trains and walked out of tunnels, according to reports.
A J train with 350 passengers and an M train with 200 riders had to back up to Essex Street to let the people out, the AP reported.
The FDNY extinguised the electrical fire, which ingited in an electrical vault at the Bowery St. station.
J and M train line service has been restored in both directions after being suspended for many hours.
Riders should expect delays.