SOUTH PORTLAND (AP) - A 22-year-old soldier from Maine who completed two tours in Iraq has been killed by "non-combat" fire while serving in Afghanistan, his grandfather said Tuesday.

There was no official confirmation of the death of Spc. Justin Buxbaum, a 2004 graduate of South Portland High School.

Buxbaum's grandfather, Donald Buxbaum of Chebeague Island, said Buxbaum's mother, who moved to Georgia last summer, was told Monday that her son was killed by a gunshot to the abdomen in a "non-combat accident."

Buxbaum's death was first reported by South Portland High School Principal Jeanne Crocker, who got the news from a relative of Buxbaum who works for the school district.

Two other South Portland graduates have died in fighting in Iraq. Marine Lance Cpl. Angel Rosa, 21, and Army Sgt. Jason Swiger, 24, were killed in March 2007.

Buxbaum joined the Army Reserve while in high school and was sent to Iraq for a nine-month tour soon after graduation, his grandfather said. He later enlisted in the regular Army, served another tour in Iraq and was deployed early last month to Afghanistan with the 62nd Engineer Battalion.