A 20-year-old man cut off his penis early Wednesday in Fremont with an X-Acto knife, police said.

Officers were called to a home on the 4300 block of Mowry Avenue about 2 a.m. by the man’s brother, said police Detective Bill Veteran.

The victim was not under the influence of drugs or alcohol, Veteran said. The reason for his action is unknown.

Officers recovered the organ. The man, whose name was withheld, was hospitalized in hopes that doctors could reattach it, Veteran said.

He also faces a psychological evaluation, police said.