The most recent of the violent incidents were two car hijackings in south Evanston, which took place hours apart last Thursday and Friday, according to Evanston police. In each case, suspects forced a woman to give up her car at gunpoint. Police later saw both cars following each other and gave chase. One car crashed and the occupant fled, leaving behind a loaded revolver recovered by police, while officers discovered the second car abandoned on the far north side of Chicago.