KANDAHAR (AFP) - Suicide attackers on Monday blew up a truck bomb and raided UN and a US development offices in Kandahar, killing five Afghans in the latest major attack on American interests in Afghanistan. The bombers struck at a compound of UN offices and US-based International Relief and Development (IRD) in the southern city. The bombing came two days after 17 people died in the deadliest attack yet in Kabul against the US-led Nato mission, including 10 Americans, and three days after a US-run base in Kandahar was targeted. One attacker detonated the vehicle outside the buildings, killing one unarmed watchman, before three others entered the compound and hid in a veterinary clinic to engage in a firefight with police, authorities said. The attackers then made their way to the UN refugee agency's offices where they shot dead three of its guards. They managed to shoot dead a local district police chief before they were themselves shot dead after more than six hours. "Fighting is over, all the attackers are dead," said Kandahar provincial police chief Abdul Raziq. UNHCR confirmed that three of its employees were killed and two other staff members were wounded, calling the attack a "tragedy". Taliban spokesman Yousuf Ahmadi said the insurgent group carried out a car bomb attack in Kandahar.