Updated

A homicide bomber disguised as a woman blew himself up at an army checkpoint in eastern Afghanistan, killing five Afghans and wounding four, police said Thursday.

The blast occurred in eastern Khost province Wednesday as Afghan soldiers were checking the assailant's vehicle, said Mohammed Ayub, the regional police chief. The attacker, sitting in the back seat, detonated explosives hidden under a woman's burqa shroud when soldiers asked to see his ID, he said.

Three Afghan soldiers, the driver of the vehicle and a farmer working nearby were killed, Ayub said. It was not clear whether the driver was an associate of the assailant or an innocent victim. Three soldiers were wounded, as well as a second farmer.

Police initially reported the blast late Wednesday but said it was caused by a land mine and that only two soldiers were killed.

Ayub accused the Taliban of being responsible for the attack.

"The bomber probably wanted to go into Khost city for a homicide attack there, but panicked and blew himself up when the soldiers started checking," he said.

The bombing is the latest in an unprecedented string of homicide attacks in recent months. The tactic represents a new and disturbing security threat four years after the ouster of the Taliban in 2001.