A woman was killed and seven people were injured, including two children, in a gas explosion on Friday in a three-story apartment building in the southern Polish city of Katowice, authorities told dpa. Four of the injured were taken to hospital but did not face life-threatening injuries. Rescue workers were still searching for a missing person, as authorities said there were nine people in the building when the explosion occurred. Prime Minister Mateusz Morawiecki, writing on Twitter, said the dead woman was 68. The fire brigade said she was found under the rubble of the collapsed house. The a…