A group of men dressed up as Santa Claus say they had to subdue a knife-wielding man on the Long Island Rail Road.

An LIRR rider posted video on Twitter Saturday night of a fight between people coming from Santa Con in the city and a man on the train who the MTA says flashed a knife and was intoxicated.

Greg Ewald of Wantagh, says he and his friend, who were heading home to the Island, are the ones in the Santa suits.

"As we were walking, heard someone screaming and just like screaming, cursing, like yelling the c-word and a bunch of other like crazy things at like a bunch of girls standing there," says Ewald.

The Nassau Community College graduate says that's when his big brother instincts kicked in.

"He just kept going and screaming at them and saying more things and then so we told him to like stop screaming at the girls, like you can't be talking to girls like that at all," says Ewald.

Ewald says the 45-year-old man threw his bag down and went after him and his friend. He says they wrestled him to the ground and held him down, with the help of some others on the train.

Police say a 22-year-old was stabbed in the leg and the suspect who flashed the knife was taken into custody at the Woodside station.

The MTA says the suspect was charged with assault, harassment and criminal possession of a weapon.

An off-duty NYPD officer who was also on the train helped restrain the suspect. The NYPD posting a picture on social media, identifying him as Officer Lam.