A woman was arrested for allegedly stabbing a fellow subway rider in the thigh with a sharp object on the Upper East Side this weekend.

Cops say that suspect, 46-year-old Nicole Brown, was sitting next to the victim, a 26-year-old woman from NJ, on a southbound 5 train at the 86th Street station around 11:30 a.m. on Saturday when the incident happened. It's unclear what prompted the stabbing, but the News reports that Brown "started muttering to herself, then jabbed the victim in the thigh with a sharp object."

Both Brown and the victim got off at the 59th Street/Lexington Avenue station, and the victim flagged down a cop who arrested Brown. She has been charged with felony assault.

The victim was taken to a local hospital, where she needed stitches for her wound. Cops add that no weapon was recovered at the scene.