Former MLB slugger and avid Twitter user Jose Canseco had an accident last night. According to his fiancé, Leila Knight, Canseco shot himself in his left hand while cleaning his semiautomatic handgun. She told TMZ the shot "ripped through the middle finger on his left hand."

TMZ reports:

[Canseco] was sitting at a table in their home cleaning the gun when it went off. [Knight] says he didn't know it was loaded—and the shot ripped through the middle finger on his left hand.

Leila tells us 50-year-old Canseco is in surgery right now as doctors desperately try to save what's left of the finger. She says the bullet tore through the bottom part of the finger and doctors have already said he'll never have full use of it again ... even under the best of circumstances.

Las Vegas police confirmed the accident.

[Photo via AP]