At least four people including three civilians were killed and two injured Monday morning when a truck bomb went off followed gunshots in Kandahar city, the provincial capital of southern Kandahar province, police said. \"So far, three civilians and a suicide attacker have been killed,\" Deputy provincial police Chief Rahmatullah Atrafi told Xinhua, adding \"The car bomb blasted at around 06:30 a.m. local time (0200 GMT) near a foreign institution\'s building in Kandahar city.\" The suicide car bomb targeted a non-governmental organization -- the International Relief and Development (IRD), a police officer near the site told Xinhua. The police source, who talked in condition of anonymity since he was not allowed to talk to media, told Xinhua that at least four Nepali nationals who serve as security guard for IRD office have also been killed in the pre-dawn attack in second sub- district of the city. The powerful blast completely destroyed the IRD office building besides damaging several houses around the blast site. IRD is a non-profit organization involved in reconstruction and development projects in Kandahar province. Gun fighting is still going on and sporadic firing still could be heard. Police forces rushed to the site and begun battling an unknown number of armed militants holed up a building near the blast site, a Xinhua reporter near the site said. \"Based on initial reports from the spot, three local civilian have been killed and two others including a Nepali National wounded in Truck-born Improvised Explosive Device (IED) attack near the IRD branch in Kandahar city,\" provincial government said in a statement released here. Two armed insurgents have taken place inside an animal clinic building and begun small arms firing small arms toward the security forces in the area, they have been facing the hard resistance by the police and will be detained or either killed shortly, the statement added. Meantime, Taliban insurgents claimed responsibility for the attack. Qari Yousuf Ahmadi, a purported Taliban spokesman in talks with local media via cell phone from undisclosed location said the outfit fighters have carried out a suicide car bomb against IRD office of foreign forces killing several foreign forces and that many Taliban still fighting with Afghan and forcing forces there. Militancy has been rampant since May this year when Taliban militants announced to launch spring offensive in the war-battered Afghanistan. Taliban claimed they carried out a suicide car bomb that killed 13 U.S. soldiers and civilian employees with the NATO-led International Security Assistance Force (ISAF) in capital city of Kabul on Saturday. The powerful car bomb occured in Darul Aman locality west of Kabul city on Saturday also killed a policeman and three civilians.