A suicide bomber has detonated explosives in front of Afghanistan's intelligence headquarters in southeast Khost province.
Eight men disguised as army soldiers reportedly attacked the base after the bomber blew himself up on Thursday morning.
US forces moved quickly to seal the area as helicopters circled over head.
Taher Khan Sabarai, the deputy governor of Khost, told Al Jazeera that some people had been killed but said he did not have details.
A Taliban spokesman claimed responsibility for the assault in a phone call to Al Jazeera.
The spokesman said the Taliban was targeting Afghan intelligence because "they are slaves working for the puppet government".
Zeina Khodr, Al Jazeera's correspondent in Afghanistan, said it was the second intelligence office to come under attack in recent weeks.
"It happened in the southern city of Kandahar just three weeks ago. An apparent target was the brother of Hamid Karzai, the president of Afghanistan.
"He was in a nearby building but he escaped unhurt."
PHOTO CAPTION
Afghanistan map locating Khost province
Al-Jazeera