The MTA is investigating a rare and alarming incident after several subway cars detached from a No. 4 train in the Bronx on Sunday evening, causing panic among passengers and halting service at the 149th Street–Grand Concourse station in Mott Haven.

Officials say the incident occurred around 5:30 p.m. when three of the train’s ten cars became separated while in motion. New York City Transit President Demetrius Crichlow described it as “an unusual incident,” emphasizing that the train’s emergency brakes activated immediately, preventing a potential disaster.

“The system itself failed as it should have — in a safe position,” Crichlow explained. “The train brakes, when applied, brought both sections of the train to a stop safely.”

Passengers described hearing a loud crash followed by sparks and a sudden jolt. “It was like a big ‘buh-boom.’ Everything went dark,” recalled Jesus Aponte, one of roughly 240 passengers onboard. Others reported being frightened and trapped until emergency crews arrived.

Above ground, anxious relatives waited for word. “He’s panicking, he’s hyperventilating,” said Bronx mother Bridgette Berkley, whose 14-year-old son was among those stuck in the detached cars.

Firefighters and police responded swiftly, ensuring all passengers were safely evacuated after electricity to the tracks was shut off. Fortunately, no injuries were reported.

The MTA has launched a full investigation and is inspecting all R-142 subway cars, the same model involved in the incident, to rule out mechanical issues. Train service at the affected station has since resumed.