A suicide car bomb targeted foreign military vehicles on Thursday morning in the Afghan capital Kabul shortly after 8:00 am (0330 GMT), police said, confirming there were casualties.
An ambulance official who declined to be named said that 10 Afghans had been evacuated from the area to be treated for injuries, without giving any further details.
Lieutenant Quenton Roehricht, a spokesman for the NATO-led International Security Assistance Force, told AFP that the mission was aware of the explosion in Kabul, but was unable to confirm if coalition vehicles had been targeted.
The last major blast in Kabul was on March 9 when a suicide bomber on a bicycle killed nine people outside the defence ministry during a visit to the city by US Defense Secretary Chuck Hagel.
The Taliban launched their annual “spring offensive” on April 27, opening a crucial period for Afghanistan as its security forces take the lead in offensives against the insurgents.
All NATO combat missions will finish by the end of next year and the 100,000 foreign troops deployed across Afghanistan have already begun to withdraw from the battlefield.