The Camp Parks officer suffered a gunshot wound to the leg when a fellow officer's gun accidentally discharged at about 9:20 a.m., said Dan Gannod, a spokesman for Camp Parks, an Army reserve training facility located in Dublin.
The injured officer received immediate medical attention because paramedics were already on scene as a precaution, Gannod said.
He was airlifted to Eden Medical Center in Castro Valley.
As of 3 p.m., the officer was in stable condition, Gannod said. The officer's name and age have not been released.
According to Gannod, the weapon used in the incident was likely a 9-mm Beretta. The officers typically train with the their service weapons.
"We expect him to recover, but we don't know how long that will take," Gannod said.