A Lawrence woman was shot and killed early yesterday morning by a bullet fired through the ceiling of her apartment, police said.Mirta Rivera, 41, was rushed to Lawrence General Hospital around 4:30 a.m. with a gunshot wound to her abdomen, Essex District Attorney spokeswoman Carrie Kimball-Monahan said, after police received a 911 call reporting a shooting.Mirta was later pronounced dead, Kimball-Monahan said.Rivera was shot by a bullet that came through the ceiling of her apartment in the three-story Exchange Street building, police said.