Unknown gunmen killed 13 police in southern Afghanistan Friday, while police arrested five suspected suicide bombers in an eastern province, officials said. The insurgents attacked a checkpoint manned by local police in the southern province of Ghazni, Deputy Governor Mohammad Ali Ahmadi told dpa. \"The gunmen attacked the checkpoint early this morning in Andar district when the policemen were sleeping,\" Ahmadi said, calling the attack \"cowardly.\" \"They killed all the 13 people stationed there and took their weapons, ammunition and a vehicle.