At least 15 people have been killed in an attack on the main UN compound in the Somali capital, Mogadishu.Local security officials said the bomber blew up explosives at the entrance gate of the UN Development Program (UNDP) office on Wednesday. Following the explosion, several heavily-armed gunmen entered the compound and opened fire. However, police forces said the situation is under control and pro-government forces have secured the building. The injured people were rushed to a nearby hospital for medical treatment, but the death toll is expected to rise as some of the injured are said to be in critical condition. Somalia’s local al-Shabab fighters often claim responsibility for deadly attack. The Somali capital has been the scene of frequent attacks since fighters were driven out of the city two years ago. Somalia had no effective central government since 1991, when warlords overthrew former dictator Mohamed Siad Barre. However, lawmakers meeting in Mogadishu, elected Hassan Sheikh Mohamud as the new president of Somalia with a big majority in September 2012.