The distraught father of the teen fatally mowed down by a Times Square madman went to the police precinct where the suspect was being held early Friday and threatened to kill him, law enforcement sources told The Post.

The dad of tragic Alyssa Elsman, 18, drove overnight with his son from the family’s home in Portage, Mich., and first went to Bellevue Hospital, where his 13-year-old daughter was recovering with a broken leg, sources said.

Completely destroyed at the loss of his other daughter, the man then went to Midtown South and began yelling that he wanted to kill drugged-up driver Richard Rojas, who struck his children with his car during a murderous rampage Thursday, sources said.

The father had to be taken to Bellevue to be calmed down, sources said.