Four Afghan guards have been killed, and eight others have been injured after three suicide bombers attacked a private security firm in southern Afghanistan, a top police official said Tuesday. The attack took place Monday night in the southern city of Kandahar when the bombers tried to storm the Supreme Global Services, which works with NATO military protecting logistic convoys, top police commander in the south Mohammad Salim Ihsas said. The first suicide bomber blew himself up at the gate of the company with an explosive-laden vehicle at 9:00 pm, Ihsas said. "Two bombers managed to spark a gun battle inside the compound that lasted for 45 minutes," he said. Four guards of the firm were killed and eight others were injured in the gunfight. "The two bombers were killed by police," Ihsas said. The logistics company is located next to the huge fortified Kandahar military airfield, home to hundreds of foreign soldiers. The Taliban claimed responsibility for the attack, saying that dozens of the guards had been killed by their fighters. Separately, unknown assailants gunned down a female employee of the local administration in Kandahar city on Tuesday, governor spokesman said. "The armed men opened fire on Razia, an employee of the local social labor ministry in Kandahar city, and killed her on the spot," Zulmai Ayobi said. They also injured her driver.