An explosion at a hall in a south Lebanon village late Wednesday injured four people, security officials and residents said. The explosion ripped through a hall attached to a Shiite Muslim mosque in the village of Shehabiyeh, causing the casualties. One person was taken to an area hospital with severe injuries, they said. The nature of the explosion was not immediately clear, with one official saying it was caused by a hand grenade that went off accidentally. A resident said a group was training on a rocket that accidentally exploded. Another resident of the village said there were four injured in the explosion. Those who commented on the matter asked not to be identified because of the security nature of the issue and its sensitivity. The village is in an area of southern Lebanon dominated by the Hizbullah terrorist Shiite organization and its allied Amal faction. Hizbullah fought Israel in the 2006 summer war. The area is part of a zone near the Israeli border that is controlled by U.N. peacekeepers. UN peacekeeping officials said they were checking reports of an incident in the village. Lebanon has experienced a series of explosions and assassinations in the last three years. But since the 2006 war, south Lebanon has been largely peaceful, except for the explosions of cluster bombs left behind from that conflict.