A 30-year-old man, armed and holed up in his father's San Francisco apartment since Sunday night, surrendered meekly after police drove him out with a dozen volleys of tear gas fired through an opening they drilled in the wall. "He walked out under his own power," Police Sgt. Jerry Senkir said in front of the Tenderloin District apartment building, 42 hours after San Francisco City College student Long Trinh locked himself in the apartment. Police said Trinh never told them his grievance. The long siege began after Trinh fired at least four shots out of his third-story window. No one was injured. Police said a rifle and a .45-caliber automatic handgun were found in the senior-citizen apartment.