At least 17 people were wounded in a suicide bomb attack on NATO troops as their truck convoy passed down the main road running between Kabul's airport and the U.S. embassy, police and health ministry officials said.
The road was closed off, and Reuters witnesses saw damaged NATO military vehicles and Western troops attending to a stricken comrade. The force of the blast rattled windows in the capital's heavily guarded diplomatic enclave and sent a huge column of grey smoke skywards.
Most NATO troops left Afghanistan last year when the combat mission ended and only a small contingent remains to train Afghan security forces. Some U.S. troops are still engaged in fighting the Taliban insurgency.
The explosion took place close to a busy shopping area, and Kabul's police chief said both foreigners and Afghan civilians were among the casualties.
"So far, 17 wounded people, including a woman and three children, have been taken to hospitals," health ministry spokesman Mohammad Ismail Kauasi said. Five of the wounded were in serious condition, he said.
It was the second major attack in Kabul since the start of Ramadan. The Taliban had rejected a request for a ceasefire during the Muslim fasting month, and the militants' summer offensive has continued unabated despite exploratory talks earlier this year between Afghan and Taliban officials in Qatar.
Last week, militants mounted an assault on the parliament as lawmakers prepared to vote on a new defense minister.
Insurgents also carried out a suicide attack the police headquarters in Helmand killing two people and wounding more than 50, according to officials in the southern province.
"The first bomber in a car detonated his explosives near the police headquarters to pave the way for two others to enter," Omar Zwak, a spokesman for Helmand's governor, said.
"Another detonated explosives attached to his body and the third one was shot and killed by security forces."