Roving, cop-hating mobs erupted in violence, taunts and gunfire in Brooklyn overnight into Sunday, leaving three officers with minor injuries. At least some of the injuries were caused by “air mail,” objects thrown down at cops from rooftops, police at the scene in Bedford-Stuyvesant told The Post. By early Sunday, 11 people had been arrested on charges of disorderly conduct. The violence came after a series of water dousing attacks on NYPD officers throughout the city this summer.