Norwegian Major General Robert Mood arrived in Syria Sunday, to head a United Nations mission overseeing a truce repeatedly violated since it went into effect more than two weeks ago. Following his arrival in Damascus, the peacekeeper called on the Syrian government and opposition to work towards ending more than 13 months of violence in the country, according to a report of DPA. Mood's arrival was underscored by persistent violence in several parts of Syria, highlighting the fragility of the UN-brokered ceasefire. At least four soldiers were killed Sunday after an explosion in a military camp south of the northern province Aleppo, the opposition Syrian Observatory for Human Rights reported. Meanwhile, four civilians were killed by Syrian troops in the central cities of Homs and Hama and in the northern town of Deir Al-Zour, added the London-based observatory. An explosion occurred Sunday in the Al Maza district of Damascus, which houses several government officials and foreign embassies, said the opposition Local Coordination Committees (LCC).