Eight policemen were held over the firing of a rocket-propelled grenade that caused the death of six children in northern Afghanistan, police said Wednesday. \"Six children between the ages 10 to 12 died in an explosion while they were swimming in a river on Friday in Doshi district,\" said Ahmad Javed Basharat, police spokesman for Baghlan province. \"Then we found out that the police had fired an RPG into the river to fish near the place where the children were swimming,\" Basharat told dpa. He said the policemen were arrested and under investigation. President Hamid Karzai ordered provincial authorities to disburse cash to the families of the victims, his office said.