A suicide car bomber killed two Afghan civilians in what appeared to be an attack on a NATO convoy in the Afghan capital on Tuesday, officials said.
"The ISAF (NATO-led) convoy was passing ... when the suicide bomber attacked them," an official who asked to remain anonymous
said.
An interior ministry spokesman said the suicide bomber used a car.
Sayed Kabir Hameedi, a senior official from the Ministry of Public Health, said two Afghan civilians were killed and 37 others wounded.
"The death toll could rise further, it is an initial report we have," he said.
The attack appeared to be the same incident as an earlier report of an explosion near the parliament building.
Police cordoned off the road near Darulaman palace, a derelict building that once housed Afghanistan's royal family, state television showed. Foreign troops were in the area.
"We are aware of an incident and we are looking into it," a spokesman for the NATO-led ISAF in Afghanistan said. The spokesman could not confirm that a NATO convoy was the target.
An increasingly resurgent Taliban has announced a spring offensive in May against government officials and foreign diplomats and troops.
President Hamid Karzai was due on Tuesday to give a news conference in the presidential palace, his first since returning from Washington, where he met US President Barack Obama to discuss strained ties between the two countries.