At least 20 passengers were killed when their commuter minibus was hit by a landmine in Lower Shabelle region of Somalia, officials said.Deputy Governor of Lower Shabelle region for Security Affairs Ali Nure Mohamed on Thursday told reporters that Al-Shabaab militants planted the landmine on the ground to blow up African Union Mission in Somalia (AMISOM) vehicles using the road, Xinnhua news agency reports."The deadly incident happened in Golweyne town this evening. Twenty civilians, mostly women on a minibus from Barawe town and heading to Marka town in lower Shabelle, were killed in a landmine blast," said Mohamed.He said that the militants intended to target AU vehicles that often use the way joining Barawe town and Mogadishu.Deadly incidents of civilians on board often take place routinely in the region due to either landmine blasts or accidents involving AMISOM troops.No group has claimed responsibility for the latest attack.