Shati arms depot kills 30 28 November 2013 Last updated at 22:43 At least 30 people have been killed in an explosion at a weapons depot in southern Libya, officials say. The blast is believed to have occurred after a group of people, reportedly including African immigrants, were trying to steal copper. A hospital near the depot in Brak al-Shati, near the city of Sabha, says it is treating the injured. Meanwhile, four soldiers have been killed in another day of violence in the restive eastern city of Benghazi. In one incident, three naval officers were killed, and six others were injured, in clashes with members of the Salafist militia group Ansar al-Sharia. Fighting broke out after naval officers arrested four people at their checkpoint when "a vehicle search found weapons and money," the army's special forces commander in Benghazi, Wanis Abu-Khamada, said. Earlier on in the day, a soldier was reportedly shot in the head in a drive-by shooting in another part of Benghazi. The government has struggled to contain militias in control of parts of Libya, and Benghazi has seen an increasing number of clashes between the army and militias. Valuable copper It is not clear what exactly caused the blast at the weapons depot in Brak al-Shati, some 650km (400 miles) south of Tripoli. State television reported that African immigrants were among a group of civilians who had stormed the depot in an attempt to steal the ammunition so they could remove its valuable copper. General Mohamed al-Dhabi told the Agence France-Presse news agency that "a group of unknown people tried to attack the depot, causing this unfortunate incident." He said 10 people had died and 15 people had been injured. The privately-owned Libyan news agency al-Tadamun said more than 30 people had been killed. Another later report put the toll at 40.