Three Afghans and the three attackers also were killed, said Sayed Abdul Ghafar Sayedzada, the Kabul criminal investigations police chief. People from at least four U.N. agencies were staying at the house, and there was some confusion about the death toll, with earlier reports saying six were dead. One of the casualties was so badly burned that he could not immediately be formally identified, said Adrian Edwards, a U.N. spokesman. 'Obviously, it was a very confused process,' he said. Later, two rockets slammed into the grounds of the Serena Hotel, said Interior Ministry spokesman Zamarai Bashari. Only one of the rockets detonated, and no one was killed. The Taliban insurgency claimed responsibility for the attack on the Bakhtar guesthouse, which is used by foreigners working for U.N. agencies in the capital. Zabihullah Mujahid, a Taliban spokesman reached by telephone, said the attack was meant as a warning not to assist with a Nov. 7 election runoff between President Hamid Karzai and former Foreign Minister Abdullah Abdullah. Election officials threw out nearly 1 million votes cast for Karzai in the first round of voting Aug. 20 because of fraud, leaving him just below the 50 percent threshold required for an outright win. 'This is our first attack on U.N. staff in Kabul because of the elections,' Mujahid said. 'And we will continue the attacks.' In a statement, Karzai condemned the attack as 'inhuman' and said he had instructed security agencies to reinforce protections at foreign installations. Edwards said at least five U.N. employees were killed and nine injured. Some of the wounds were severe, and the death toll could rise, he said. 'This is a very dark day for the U.N. in Afghanistan,' said Kai Eide, the U.N. special representative here. He said the United Nations would review its security measures but would not be deterred from 'continuing all its work to reconstruct a war-torn country and to build a better future for all Afghans.' Sayedzada said the three attackers entered the building at about 5:50 a.m., looking for foreigners. A rapid-reaction force responded, and the militants were killed within 45 minutes, he said. But sporadic gunfire, some of it intense, could be heard for more than an hour. Two Afghan security force members were killed during the attack, and three were injured, an Interior Ministry statement said. An Afghan civilian living in a nearby house was killed in the crossfire, Sayedzada said. Afghan security officials rescued seven people from the guesthouse, which caught fire during the attack, Sayedzada said. Police brought out a woman, who was in tears, and put her in a white U.N. vehicle. An Associated Press photograph showed an injured man being carried out piggyback. (Begin optional trim) The embassy released a statement: 'The United States condemns the attack today on a guesthouse in Kabul, which killed at least six United Nations employees, including one American, and injured many others. This brutal attack on our international partners and friends, who were working to help build a secure and peaceful future for all Afghans, leaves us shocked and saddened. Attacking civilian workers will not lessen our determination to support the Afghan people and their election process. Our sympathies are with the families who have lost loved ones in this violence.' None of the victims was identified, pending notification of relatives. The attacks came a day after eight U.S. troops died in two bombings in southern Afghanistan. At least 54 U.S. service members have been killed in October, according to the independent Web site icasualties.org, making it the deadliest month for Americans in the eight-year war. The previous high was around the election in August, when 51 Americans were killed. (End optional trim) Special correspondent Karim Sharifi in Kabul contributed to this report. 