Three to 12 people may have been shot dead and more than 20 injured by three gunmen who, shooting semiautomatic rifles, burst into the San Bernadino Inland Regional Center for the disabled Wednesday night. They were described as masked and wearing body armor under military attire. A bomb squad’s robot was sent into one of the three buildings of the huge center to defuse a suspected bomb. All three gunmen, none of them identified, apparently escaped in a black SUV, after which the shooting stopped. Police have put out a call for the vehicle, and appear to be in the dark about the motive for the attack or the whereabouts of the shooters. They have not given out any confirmed casualty figures. A field hospital treated the wounded outside the regional center, which cares for tens of thousands of disabled people and employs more than 600 personnel.