PALMER - A Thorndike man is believed to have killed himself after accidentally shooting his girlfriend while unloading his gun Saturday night.

Police initially responded to a 911 call reporting a woman had been shot at about 10:15 p.m. at a home at 311 River St. When they arrived they found the 21-year-old female suffering from a gunshot wound to her back, James Leydon, spokesman for Hampden District Attorney Anthony Gulluni said.

"The female victim, who was alert, stated her boyfriend had (accidentally) shot her while he was unloading his firearm," Leydon said in writing.

She was taken to Baystate Medical Center, in Springfield, and is being treated for life-threatening injuries, Palmer Police said.

While the woman was being treated, officers began searching for her boyfriend. They soon found the 24-year-old man outside and dead from an apparent gunshot wound to the head, Leydon said.

The names of the victims have not been released yet, Leydon said.

Leydon did not say if the man had a permit to own a firearm.

Massachusetts State Police Detective Unit assigned to the Hampden District Attorney's Office and Palmer Police detectives are continuing to investigate the double shooting.