Last week, a brave bystander suffered a facial injury while attempting to intervene in a conflict aboard a train traveling through a major Manhattan station, according to police and witness accounts.

The incident unfolded on a southbound 4 train near the 14th Street Union Square station around 2:40 p.m. on Friday. The victim noticed a man wearing glasses and carrying a backpack embroiled in an intense argument with another passenger, sources revealed.

As the good Samaritan tried to de-escalate the situation, the aggressor turned on him, slashing his face, officials and insiders reported.

The injured man was transported to Bellevue Hospital, where medical staff listed his condition as stable, authorities confirmed.

The assailant fled on foot and, as of Wednesday, remained at large, according to police statements.

Captured surveillance images depict the suspect as a man with a dark complexion, dressed in a gray Nike tracksuit and holding a cell phone, seemingly engaged in a verbal altercation with someone on the train.

Anyone with information on his whereabouts is asked to call the NYPD’s Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).

The public can also submit their tips by logging onto the Crime Stoppers website at on X @NYPDTips.