A suicide bomber attacked an Afghan military bus in Kabul Sunday, killing four people and injuring 20 others, officials said. The attack happened at about 7 a.m. local time as the bus, which was carrying air force officers, approached Kabul's eastern Karte Naw district, the Los Angeles Times reported. Two Afghan army officers and two civilians were killed in the blast, Afghan Defense Ministry spokesman Zahir Azimy said. The Taliban has claimed responsibility for the attack.