(AP) - A gunman killed a Virginia Tech policeofficer Thursday at a campus parking lot and then apparently shothimself to death nearby in a baffling attack that shook up theschool nearly five years after it was the scene of the deadliestshooting rampage in modern U.S. history.The shooting took place on the same day Virginia Tech officialswere in Washington, fighting a government fine over their allegedmishandling of the 2007 bloodbath where 33 people were killed.Before it became clear that the gunman in Thursday's attack wasdead, the school applied the lessons learned during the lasttragedy, locking down the campus and using a high-tech alert systemto warn students and faculty members to stay indoors.The officer was killed after pulling a driver over in a trafficstop. The gunman - who was not involved in the traffic stop -walked into the parking lot and ambushed the officer. Police didnot know what the motive was.The officer was identified as Deriek W. Crouse, a 39-year-oldArmy veteran and married father of five who joined the campuspolice force about six months after the 2007 massacre, the schoolsaid. He previously worked at a jail and a sheriff's department. While authorities wouldn't reveal specific details about thegunman or his identity, they released a timeline of events.At about 12:15 p.m., the officer called in the traffic stop.After a few minutes passed without hearing from the officer,dispatch tried to get in touch with him, but didn't get a response.About 15 minutes later, police received the first call from awitness who said an officer had been shot at the Cassell Coliseumparking lot and the gunman had fled on foot. Local, state and federal officials responded immediately. At 1p.m., an officer saw a suspicious man in a parking lot known as TheCage. The man had a gunshot wound and a gun was nearby.Authorities said they responded to numerous other calls ofsuspicious activity, but found no threats and lifted the campuslockdown, about four hours after the initial alerts.Asked if police were still looking for the shooter, state policeSgt. Robert Carpentieri said: "I think the investigators feelconfident that we've located the person. I can't give you specificsand I don't want to confirm that but you can kind of read betweenthe lines so I won't specifically address that question." The officer had served four years on the campus police force,which has about 50 officers and 20 full- and part-time securityguards. State police were still investigating whether the officerhad been specifically targeted.