KABUL, Afghanistan — Taliban insurgents pulled some 50 passengers off a bus in southern Afghanistan and beheaded as many as 30 of them after accusing them of being soldiers traveling in civilian clothes, Afghan officials in the region announced on Sunday.

The police chief of Kandahar Province, where the attack occurred on Thursday, said that of six bodies retrieved so far, all had been beheaded, mutilated and dumped. The police had received information that 24 other people had been killed but had yet to find their bodies, the police chief, Gen. Matiullah Qati, said.

The attack was on the main road running from the southern city of Kandahar to the western town of Herat, General Qati said. It took place in Maiwand District, which is known as an area with a significant Taliban presence, where attacks on military convoys are frequent. The road is also the main route for British and Afghan army troops traveling to Helmand Province, where the insurgency is strongest.

The attack follows a pattern of intimidation and brutality that Taliban insurgents have pursued, spreading terror in an effort to undermine support for the Afghan government.