A man barged into a Jewish nursing home in the Bronx and terrorized residents Saturday afternoon, beating one and threatening to kill him while going on an anti-Semitic tirade, police sources said.

Alen Califano, 41, went to the New Jewish Home on University Avenue in Fordham Heights and asked an employee if he could use the restroom around 3:30 p.m.

Califano then crept onto an elevator, went to the fourth floor and entered the room of a 68-year-old, where he smashed the man’s doorbell and knocked a television set to the ground.

“He looked like one of those big ass mafia hitmen,” Charles Davis, 68, told The Post.

“He went in his pocket, I thought he was going to pull out a weapon. He pulled out some reefer. He lit it up and was smoking his ass off in here.”

“I got a lot of plants in my room. He threw them all over the bed, all over the floor,” Davis said.

Califano then went into another room and hurled the extinguisher at an 84-year-old Jewish man, the sources said.

He bashed the man in the head while repeatedly shouting, “I’m going to kill you, you mother f—ing Jew,” the sources said.

Califano was arrested as he tried to leave. He faces multiple charges, including burglary and assault as a hate crime.

A spokeswoman for the nursing home said the security guard who allowed the man into the building has been fired.

“There is nothing more important than the health and safety of our residents,” said Leslie Hoot.

“We are all relieved that our resident – a wonderful, kind and gentle man – did not sustain serious injury. We are providing him with comfort, counseling and excellent quality care.”