Two LAPD detectives were hospitalized after being shot on their return to a police station early today; authorities are now searching for the gunman who ambushed the cops. Three people have been detained following the attack, which involved an exchange of shots. "When they swiped their key card" to get through a driveway gate, "somebody just started shooting at them from behind," said LAPD Commander Andy Smith, per NBC Los Angeles. One officer was grazed in the back of the head, while the other was hit in the hand, officials say; they've since been released from the hospital. Police have closed off a 25-block area near the site of the attack.