A massive blast rocked Kabul's diplomatic quarter during the morning rush hour on Wednesday the latest attack to hit the Afghan capital.
A huge plume of smoke could be seen rising from the area but it was not clear what the target was and there was no immediate confirmation of any casualties.
Witnesses said dozens of cars were blocking roads and some wounded people could be seen.
There was no immediate claim of responsibility, but the attack came as the resurgent Taliban are stepping up their annual "spring offensive".
The Islamic State group has also claimed responsibility for several recent bombings in the Afghan capital, including a powerful blast targeting an armoured NATO convoy that killed at least eight people and wounded 28 on May 3.
Pentagon chief Jim Mattis has warned of "another tough year" for both foreign troops and local forces in Afghanistan, where more than one third of the country is outside of government control.
The blast was the latest in a long line of attacks in the Afghan capital. Kabul province had the highest number of casualties in the first three months of 2017 thanks to multiple attacks in the city, with civilians bearing the brunt of the violence.