A 70-year-old man slashed a 68-year-old woman in the face with a knife after a brief dispute at a Brooklyn subway emergency exit Saturday, police said. The incident came as serious assaults across New York City’s transit system continued to rise, increasing 12% from the same period last year.

The altercation unfolded around 9 a.m. on the mezzanine of the Sheepshead Bay station, served by the B and Q lines. According to police, the man was holding open an emergency exit door when he got into an argument with the woman.

The man then pressed a knife against the woman’s face, cutting her and leaving her bleeding, a police source said.

The suspect escaped aboard a southbound Q train, police said. A person of interest was later taken into custody, though charges were still pending, according to the source.

The woman declined medical treatment at the scene.

Emergency exit doors are sometimes held open by people who ask entering riders for money in exchange for access to the station.

Felony assaults in the city’s transit system have climbed 12% so far this year, reaching 525 compared with 470 during the same period last year. Misdemeanor assaults have risen 16%, from 1,120 to 1,304, according to the latest NYPD data available through Oct. 13.

Compared with two years ago, felony assaults are up 18%; compared with seven years ago, they have nearly doubled, rising 94%. Misdemeanor assaults have increased 11% over two years and 25% over seven years, NYPD figures show. The department did not provide the underlying totals for those earlier periods.

Overall transit crime is up 2% this year, while arrests in the transit system have fallen 5%, declining to 22,847 from 23,977 at the same point last year, according to police data.