A person was shot by an MTA employee during a dispute at a subway station in Brooklyn Tuesday night, according to police.

The shooting occurred at the Union Street station in Park Slope around 9 p.m. after a man got into a dispute with two MTA employees on the subway, the NYPD said.

“This is obviously and fortunetely an unusual occurance,” the NYPD’s chief of transit, Michael Kemper, said at a press conference Tuesday just after 11 p.m. 

Two MTA employees were in uniform with MTA patches Tuesday evening waiting for a train at the Atlantic Avenue-Barclays Center station on a southbound R platform, according to Kemper.

One employee is a revenue electronic maintainer who fixes MetroCard machines, Kemper added. The other employee is a transit revenue collector, who is armed and acts as security for his coworker.

While the employees were waiting for their train, a man approached them and threatened to beat them up, according to Kemper. 

The man followed the two employees onto their train, Kemper said, and the dispute carried on until the Union Street station, where the employees exited the train — the man followed.

The dispute continued onto the mezzanine level of the station, according to Kemper, where the armed employee pulled out his gun and gave verbal commands for the man to back up. The man did not follow the armed employee’s orders, and the employee shot him in the chest.

The man, who is 39 years old, was hospitalized in critical condition, police said.

The employee who shot the man is a 21-year veteran of the MTA. The department has 274 armed collection agents whose job it is to accompany the employees who repair MetroCard machines, according to the president of New York City Transit, Richard Davey.

“They are there to provide security when they are inside the machine, which of course has cash and other potential uses for fares,” Davey said.

There was surveillance video of the shooting, police said.