BASRA, Iraq (Reuters) - At least three people were killed and more than 50 injured in a gas pipeline explosion in southern Iraq, police sources said on Saturday. The military said in a statement that the cause of the blast was not known. It said nine Shi’ite militia fighters were among the wounded and two children had been killed. Police sources said the blast, near the southern city of Samawa, 270 km (170 miles) south of Baghdad, occurred along a stretch of pipeline that goes near a militia camp. Gas officials said the pipe there had seen leaks in the past.