KANDAHAR, Afghanistan — A suicide bomber blew himself up Thursday on a crowded street near a police vehicle in southern Afghanistan, killing four civilians and wounding 25 people, officials said.

The suicide bomber, who was on foot, struck near the vehicle of highway police commander Rozi Khan outside the city of Qalat, said Zabul provincial police chief Noor Mohammad Paktin.

It wasn't immediately clear if Khan was hurt.

Zabul governor Dilber Jan Arman said four civilians were killed and 23 civilians and two policemen were wounded. He said the bomb hit a crowded street and injured shopkeepers and passers-by.

Abdul Satar, an official at the Qalat hospital where the victims were sent for treatment, reported four police wounded.

Meanwhile, eight suspected Taliban militants were killed and a policeman wounded in a joint operation by the Afghan police and army Tuesday in western Farah province, said Gov. Abdul Samad Stanikzai.

NATO said there were some Taliban casualties on Wednesday in the south when NATO troops launched a "precision air strike against a known Taliban command post" in an isolated area of the Panjwayi district of Kandahar province.

Local officials said they did not know yet the number of casualties from the air strike.

Nearly 4,000 deaths have been reported in insurgency-related violence this year in Afghanistan, including some 300 civilians.