A U.S.-led coalition convoy hit and killed a boy in Kabul, while Afghan and coalition forces arrested five suspected Al Qaeda in eastern Afghanistan on Wednesday.

Acting on intelligence, the joint forces arrested the "Al Qaeda associates" during a raid on a compound in Nangarhar province's Chaparhar district, a coalition statement said. It said no shots were fired and no serious injuries reported.

On Tuesday in Kabul, a coalition convoy was passing through a bazaar when the boy stepped into the road from behind a large truck, a coalition statement said. The convoy stopped to provide first aid and the boy was evacuated for medical care, but died of his injuries, it said.

In the volatile south, gunmen kidnapped Habib Rahman, the agriculture department director of Zabul province, as he was traveling by car from neighboring Ghazni province on Tuesday, said Ali Shah Ahmadzai, Ghazni's police chief.

Purported Taliban spokesman Qari Yousef Ahmadi claimed responsibility for the kidnapping in a phone call from an undisclosed location. Ahmadi said Taliban authorities will decide Rahman's fate.

In western Herat province, meanwhile, Afghan troops searched a suspicious guarded compound on Tuesday and discovered 18 rocket propelled grenades, 27 AK-47 weapons and Afghan police uniforms, a coalition statement said. The guard later confessed that he commanded more than 100 Taliban fighters, it said.

Also Tuesday, a powerful remote-controlled bomb destroyed a U.N. vehicle in southern Afghanistan's main city, killing four Nepalese guards and an Afghan driver, officials said.

The attack on a three-vehicle U.N. convoy in Kandahar was the bloodiest in Afghanistan for the world body since the hard-line Taliban militia's 2001 ouster. It showed how violence still impedes much-needed reconstruction.

The convoy was beside a canal when unidentified assailants detonated the charge. It hit a gray sport-utility vehicle, killing the four guards and their driver, police and the U.N. said.

An Associated Press reporter saw two charred bodies on the road nearby. The blast blew off two of the car's doors and gouged a crater in the road.

No one immediately claimed responsibility.

The attack came a day after a Human Rights Watch report accused Taliban militants of committing war crimes by targeting civilians.

The rights group said militants killed nearly 700 Afghan civilians in 2006 — more than three times the civilian deaths attributed to U.S. and NATO forces, which have been criticized for using excessive force in civilian areas.