A suicide bomber boarded a crowded army bus and detonated a huge explosion that ripped off the roof and blasted out the sides, killing at least 27 people and wounding 21 on Saturday, officials said.
Dozens of civilians and police officers picked through the charred hull of the bus immediately after the blast, searching for bodies.
A high-ranking Afghan army medical official said 27 bodies had been taken to two hospitals. He asked not to be identified because he was not supposed to talk to the media.
"For 10 or 15 seconds, it was like an atom bomb, fire, smoke and dust everywhere," said Mohammad Azim, a police officer who witnessed the explosion.
Sulahdin, an army officer at the scene who goes by one name, said there were more than 50 people on the bus at the time of the explosion, around 6:45 am (0815 IST).
Dozens of civilians and police officers removed bodies from the bus.