MANHATTAN, N.Y. (WABC) -- An off-duty NYPD sergeant was suspended after he got into a fight in a Billy Joel concert in Manhattan back in August.The NYPD said Sgt. Joseph Brennan, punched another person attending the concert at Madison Square Garden on Aug. 7. The victim was not seriously hurt.Police said it's believed Brennan and the victim did not know each other, and a dispute between the two escalated into a fight.An NYPD Internal Affairs investigation resulted in Brennan being suspended without pay and being charged with assault and harassment. He was arrested on the charges Wednesday morning.