Gunmen believed to be dissident Republicans fired at three Police Service of Northern Ireland vehicles in Belfast late Thursday, authorities said. No officers were injured. Chief Superintendent George Clarke appealed for public help in apprehending the shooters and said the attack would be treated as attempted murder, UPI reported. The attack occurred in the Ardoyne neighborhood in north Belfast. Earlier Thursday, two men who had been detained for questioning about an abortive car bombing in Belfast were released without charge. On Nov. 24, a car was hijacked in the Ardoyne and the driver forced to take the bomb to the center of the city. The driver managed to ditch the car and warn the authorities about the bomb. The bomb partially detonated without injuring anyone.