Monday's evening subway commute was disrupted by what the MTA says were mechanical problems.

The MTA alerted riders on its website just before 7 p.m. that they should allow for additional travel time because of a train with mechanical problems. 

Some riders say they heard a sound similar to that of an explosion on the No. 5 train, followed by a flash of light.

One rider says her train was stopped in the tunnel for about a half-hour as MTA employees notified riders that there was an emergency in the train in front of them. After those 30 minutes passed, that rider says she and the train's other passengers were directed to get off the train and onto the platform so they could be directed to another train.

There were about five subway service changes around 7 p.m. Monday, according to the MTA's website.

Some northbound No. 2 trains were running on the No. 1 subway line from 96th Street to the 137th Street-City College stop. Some northbound No. 2 trains were running on the No. 3 subway line from 135th Street to the Harlem-148th Street stop.

The MTA updated its online post around 7:38 p.m. to notify riders that service on the No. 2, 3, 4 and 5 trains had resumed normal service.

News 12 reached out to the agency for more details on the mechanical issue but has not yet heard back.