Two Baltimore police officers were shot, one of them fatally, when gunfire erupted early Sunday outside a club near downtown. Six people in all were shot and two killed. Three sources said detectives are exploring whether the officer who was killed was shot by another officer amid a chaotic scene outside the Select Lounge in the 400 block of North Paca Street. The incident occurred at about 1:15 a.m. when police were called to break up fights and control a crowd outside the club near Franklin Street in the Seton Hill neighborhood, said Police Commissioner Frederick H. Bealefeld III.