At least one suicide bomber blew himself up at the entrance of a guesthouse in central Kabul on Tuesday, police told a foreign news agency, killing a guard. "We know that at least one suicide bomber attempted to enter the guesthouse. He was encountered by a guard at the guesthouse and detonated. The bomber and the guard were killed," said a Kabul police officer on condition of anonymity. A spokesman for Kabul police said two suicide bombers blew up vests packed with explosives. Only one blast was heard by local residents in the Taimani district of downtown Kabul.