A New York Islanders fan slashed the face of a New York Rangers fan outside Madison Square Garden following his team's blowout loss Wednesday night, police said.

The incident occurred as fans of the regional rivals were leaving the arena at around 9:45 p.m. The Rangers won 5-0, the New York Daily News reported.

A witness said the alleged slasher, who was wearing the jersey of former Islanders power forward Todd Bertuzzi, took out a blade and slashed the Rangers fan in the face and neck. It was not immediately clear what prompted the confrontation and the suspect was not identified in reports.

“I responded with the cops,” said an MSG security guard, who didn’t give his name. “It was two guys in hockey jerseys fighting it out. One was cutting the other. When we got there, he was bleeding and he was down.”

The victim was taken to a hospital. His condition was not immediately known.

“He was down and out,” Richard Eubanks, another witness, said of the victim. “He was bleeding from his nose to his cheek. Someone was holding his neck steady while another guy called 911.”

He said several fights broke out throughout the evening.

“It was Islanders vs. Rangers, and it was a Rangers fan down," Eubanks said. "There were fights all night long. It’s sad. It was a good game.”

The rivalry for both teams has escalated in recent years following the Islanders 2015 move to Brooklyn after calling Long Island home for several decades.