The car bomber attacked a military convoy just a couple of hundred yards from the embassy compound at about 8am (0330 GMT) on Tuesday, causing a huge blast that rattled the neighbourhood, the police said.
Faird Afzalai, chief of criminal investigations for Kabul's police, confirmed reports that the bomber targeted a foreign convoy. Three of the victims were Afghan soldiers. The blast happened near the country's Supreme Court on a busy road that runs from the heavily fortified US embassy to Kabul airport.
In the aftermath of the explosion, which occurred during heavy rush-hour traffic, Afghan and foreign troops secured the area as fire and rescue vehicles moved in. At the side of the road, foreign troops gave first-aid to some blood-stained fellow soldiers from the convoy. About a half dozen cars stood damaged, and investigators inspected an empty black 4WD vehicle, its windows smashed and exterior pockmarked with shrapnel.
One vehicle from the convoy was thrown off the road and destroyed by the blast. The Taliban claimed responsibility for the attack in an emailed statement to journalists and via a recognised Twitter account.
A Polish military spokesman later said one Polish soldier was killed and two others were wounded but were not in danger. Lieutenant-Colonel Piotr Walatek identified the dead soldier as Sergeant Rafal Celebudzki, who was driving one of the convoy's vehicles.