The bombing, which took place on Sunday, is the latest insurgent attack after foreign forces ended their combat mission there.
Bombers hit a checkpoint manned by members of the Khost Provincial Force, an Afghan unit that guards Camp Chapman, said Youqib Khan, the deputy police chief in Khost province. It wasn’t immediately clear whether the bomber was trying to get on to the base or what led to his attack, Khan said.
A US defence official said Chapman is an Afghan base with some American special operations forces there.
The bodies of at least 26 Afghan civilians was received at a local hospital, mostly women and children including eight members of a single family, said Dr Hedayatullah Hamedi, the province’s health director. He said the blast also wounded nine civilians.
“The explosion was so loud and strong that almost all of the city of Khost was shaken by the blast,” provincial police chief General Faizullah Ghyrat said.
A statement issued by the Khost provincial governor’s office offered different casualty numbers, saying that 33 people were killed – 27 civilians, including 12 children, and six members of the Afghan security forces. Another 12 members of the Afghan security forces were injured, according to the statement. The discrepancy in the casualty numbers could not immediately be reconciled.
The suicide bomber carried out his attack when many civilian vehicles were waiting to pass by on a main road, an Afghan police officer said. He said the civilians killed and wounded in the attack were in vehicles waiting for their turn to pass.
Foreign and Afghan forces blocked journalists and police from accessing the site after the blast. Pentagon officials referred comment to Nato authorities in Afghanistan. In a statement, Nato said “no US or coalition personnel were injured as a result of the attack”, without elaborating.
No group immediately claimed responsibility for the blast in the city of Khost, near Afghanistan’s eastern border with Pakistan.
Since US and Nato troops ended their combat mission at the end of last year, local troops have been taking the brunt of attacks by the Taliban and other insurgent groups. Camp Chapman, named after the first US soldier killed in combat in the war in Afghanistan, sits near Forward Operating Base Salerno, a large Soviet-built airfield that was targeted by a Taliban truck bombing in June 2012.
Camp Chapman was the site where seven CIA employees and a Jordanian intelligence officer were killed in a Pakistani Taliban suicide bombing in December 2009. Six more agency personnel were wounded in what was considered the most lethal attack for the CIA since the war in Afghanistan began in 2001 and possibly even since the 1983 embassy bombing in Beirut. It’s not clear whether the CIA still operates out of Camp Chapman.
Meanwhile, also on Sunday, Afghan security officials said a pair of roadside bombings killed at least 12 civilians in the country’s east and north. The Taliban frequently uses roadside bombs and suicide attacks to target Afghan army or police forces across the country.
Islamic State has also released an online audio clip they claim comes from Hafeez Sayeed, the leader of an Afghan affiliate that authorities in Nangahar province say was killed in a US airstrike last Friday.