A suicide bomber dressed as a security guard blew himself up Wednesday in a street in the Afghan capital, killing himself and two other people, authorities said. The attacker set off the explosives attached to his body around 8 a.m. after he was noticed by security guards in the neighborhood, said Sediq Seddiqi, a spokesman for the Afghan interior ministry. The blast took place in a district that houses international organizations, diplomats and senior government officials. Afghan authorities don't know what the bomber's intended target was, Seddiqi said. One of the people killed was a security guard and another was a civilian, Seddiqi said. One person was wounded in the attack, he was quoted as saying by CNN.