A suicide attacker driving an explosives-packed vehicle has targeted a Nato military convoy in the Afghan capital, Kabul.
Police on the scene said casualties are expected.
“It was a suicide car bomber, there are casualties but it is too early to know the extent of the damage,” said Kabul deputy police chief Sayed Gulagha.
A spokesman for Nato in Afghanistan, US Army Col Brian Tribus, confirmed that a coalition convoy had been attacked.
The explosion took place on the main airport road in eastern Kabul, sending a huge plume of black smoke into the air above the city.
It happened as government employees were leaving their offices and roads were choked with vehicles, as the working day is shortened during the Ramadan fasting month.
The incident comes a week after an audacious attack on the nation’s parliament, which highlighted the ability of insurgents, who have been fighting to overthrow the Kabul government for almost 14 years, to enter the highly fortified capital to stage deadly attacks.
Also on Tuesday, a suicide attack on the police headquarters of southern Helmand province killed up to three people and wounded more than 50, including policemen, officials said.
Omar Zawak, spokesman for the governor of Helmand province, said most of the injured were women and children.
Police spokesman Farid Hamad Obaid said a car packed with explosives was driven into the back wall of the police headquarters in an attempt to breach a gate. All the gunmen fled the area, he said.
Meanwhile, in eastern Paktya province, three people were killed and one was wounded when their vehicle hit a roadside mine, provincial police chief Zalmai Oryakhel said.