“A suicide car bombing near a U.S. military base in eastern Afghanistan that once hosted CIA employees killed at least 17 civilians Sunday, local officials said, the latest insurgent attack after foreign forces ended their combat mission there.

The bombing hit a checkpoint manned by members of the Khost Provincial Force, an Afghan unit that guards Camp Chapman for the American forces there, said Youqib Khan, the deputy police chief in Khost province. It wasn’t immediately clear whether the bomber was trying to get onto the base or what led up to his attack, Khan said.

A local hospital received the bodies of at least 17 Afghan civilians, most women and children, said Dr. Hedayatullah Hamedi, the province’s health director. He said the blast wounded six civilians, two of whom were in critical condition Sunday night, and that the death toll could rise.

“The explosion was so loud and strong that almost all of the city of Khost was shaken by the blast,” provincial police chief Gen. Faizullah Ghyrat said.

The suicide bomber carried out his attack when many civilian vehicles were waiting to pass by on a main road, said an Afghan police officer who spoke on condition of anonymity as he wasn’t authorized to discuss the attack. He said the women and children 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 U.S. 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 U.S. 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.”

Nasir Shansab, author of the book Silent Trees: Power and Passion in War Torn Afghanistan.