A Veterans Day brawl at a Turtle Bay bar ended with an Army soldier allegedly slashing a Marine in the back, according to witnesses and police sources.

A group of men in Army fatigues was drinking at Turtle Bay NYC on Second Ave. near 52nd St. around 7:45 p.m. when an argument allegedly broke out with a man wearing a Marines T-shirt, witnesses told the New York Daily News, which added that police sources claimed that 35-year-old Marine veteran Alfonso Matos had admonished the group for drinking in uniform before things turned bloody.

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“They were being annoying in the back of the bar. They were waving American flags,” said a Turtle Bay patron to the Daily News. “It turned into a beef.”

The situation escalated to a physical fight outside the bar, and Matos was stabbed in the shoulder, police said in a related NBC report.

“They were all boasting and drinking a lot. The biggest guy there had an American flag in his hands,” said Jesus Ferrer, 45, a Bronx medical coder, in the Daily News report. “The big dude with the beard [Matos] said he could fight anyone in the place. … They went outside, and next thing you know, he was standing against the wall with blood dripping down his back.”

The suspects fled the scene, NBC reported, adding that police are investigating and no arrests have been made.

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Matos was rushed to Bellevue Hospital in stable condition, police stated in the Daily News report. The bar was closed for several hours, reopening after midnight.