Seven children were killed when a water tank made of bricks and cement collapsed in Pakistan's Khyber Pakhtunkhwa province, rescue officials said.The children aged between four and 12 years were playing near the tank in Mohmand district when the walls collapsed on them on Saturday, Abdullah Mohmand, spokesperson of the state-owned Rescue 1122 in the district, told Xinhua news agency.He added that the children remained trapped under the debris of the tank until the residents and rescue teams retrieved the bodies and the one injured from the rubbles.He said that the tank was in a dilapidated condition, and locals used to fetch water from it for drinking and other purposes.The spokesperson added that on Saturday some people including parents of the kids were filling water in their cans when the incident took place.The injured child was shifting to a nearby hospital where his condition is stable.