A suicide bomber has struck near a U.S. base in eastern Afghanistan, killing three Afghans.
The Taliban claimed responsibility for the attack, which took place Wednesday near the facility known as Forward Operating Base Chapman in Khost province.
Authorities say the bomber detonated a van full of explosives while a guard was checking the vehicle near the entrance of the base. The guard and two nearby civilians were killed.
Afghan Taliban spokesman Zabihullah Mujahid claimed "more than a 100 joint enemies were killed or wounded." The insurgent group is know to exaggerate casualty figures.
There were no reports of NATO casualties in Wednesday's blast, which also left seven people wounded.
The attack is not the first time the American base in Khost has been a target of militants.
In 2009, seven U.S. Central Intelligence Agency employees and a Jordanian worker were killed at the base in a suicide bombing by an al-Qaida-linked agent.
The al-Qaida-linked Haqqani militant network is known to be active in Khost province, which borders Pakistan.
The attack comes two days after a female Afghan police officer shot and killed an American adviser in Kabul, an incident that once gain raised concerns about the ability of Afghan authorities to manage security after most foreign troops pull out in 2014.
Afghan authorities said the female shooter is an Iranian national, but there was no initial evidence that she had ties to militant groups.