BEIRUT (Reuters) - Three people were killed on Wednesday when an explosion ripped through a building in eastern Lebanon, a stronghold of the Shi'ite Muslim militant group Hezbollah, a medical source said. Hezbollah forces quickly cordoned off the area and prevented journalists from entering the town of Nabi Sheet, 30 km (18 miles) south of the regional centre of Baalbek. The cause of the explosion was not immediately clear. One source said the blast occurred in a weapons cache but a security source said the building was used to store car parts. ...