What started as an ordinary evening commute on a Brooklyn bus exploded into chaos when a woman allegedly assaulted a 72-year-old passenger during a baffling meltdown over a seat, according to police and law enforcement sources.

The incident unfolded just after 6 p.m. on Jan. 29 aboard a crowded B6 bus near Glenwood Road and Nostrand Avenue in Flatbush. Witnesses told investigators the elderly woman briefly stood up and then sat back down — a routine movement that somehow sent a stranger into an uncontrollable fury.

Instead of brushing off the moment, the attacker marched toward the senior and allegedly began pummeling her without warning. Police say the suspect punched the victim several times in the face, leaving passengers stunned as the assault played out in the middle of the bus.

Paramedics rushed the injured woman to Mount Sinai Brooklyn, where she was listed in stable condition. Authorities say she is expected to recover, but the attack has rattled regular riders who rely on the B6 route every day.

The suspect wasted no time fleeing, bolting out of the bus and running north along Nostrand Avenue before officers arrived. She has not been identified, and the NYPD is now asking the public for help.

On Thursday night, police released a series of close-up photos of the woman they say is responsible for the assault. She is described as having a dark complexion and was last seen wearing a light-colored bubble jacket, black-and-white striped pants, and a hat. Investigators believe she may frequent the Flatbush area.

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