Police are still investigating how a 15-year-old Coon Rapids boy got a handgun Monday, fatally shooting himself after he accidentally shot and wounded his girlfriend.

According to the Anoka County Sheriff’s Office, the boy was “playing” with a .357 magnum revolver when it went off accidentally about 4 p.m. Monday in his apartment, shooting his 14-year-old girlfriend once in chest, before the bullet became lodged in her head.

The girl remained hospitalized in good condition Tuesday. The Star Tribune is not naming the teens because they are minors and not charged with a crime.

Police found the boy with an apparent self-inflicted gunshot wound to his head, lying on the ground between Winchester Place Apartments off Robinson Drive NW. and the nearby Northwest Passage Alternative High School. The same handgun and one of the spent casings were nearby, Anoka County Sheriff’s Office spokesman Cmdr. Paul Sommer said Tuesday. No other weapons were found by authorities.

Police are continuing to investigate where the gun came from and how the 15-year-old got it.