A crazed-looking straphanger stabbed another subway rider in Crown Heights, according to police.

The unknown woman stabbed the other rider twice in the arm and once in the abdomen in the Utica Avenue subway at about 2:10 p.m. Friday before taking off, according to NYPD.

It was unclear what caused the dispute between two women, who were acquaintances, while on the southbound 3 train platform, cops said.

The victim was taken to an area hospital, where she was listed as stable.