Afghan officials say gunmen have killed at least 13 people in a late-night attack on passengers traveling on a highway in central Afghanistan.
Several attackers opened fire on vehicles around 1:00 a.m. local time Tuesday, said Wardak provincial governor spokesman Attahullah Khogyani.
At least some of the victims were traveling on a bus that was headed toward southern Afghanistan.
A motive has not been determined, and no group has claimed responsibility for the attack, which is the latest to target buses in Afghanistan.
Last month, gunmen abducted 30 members of the country's Hazara Shi'ite Muslim minority group who were traveling on buses in Zabul province.
The abductees remain missing.
Hazaras have been the targets of bombings, kidnappings and other attacks in recent years by Taliban extremists and other Sunni extremists in Afghanistan and Pakistan.
Afghanistan continues to experience regular violence, even as the United States continues to wind down its formal military presence in the country following nearly 14 years of war.