Afghan officials say a suicide car bombing followed by other explosions and gunfire has rocked the capital.
Authorities say the attack targeted a traffic police complex in Kabul early Monday.
Police say two of the assailants were killed at the entrance. They say at least one other attacker has entered the building.
The Taliban has claimed responsibility for the attack.
It is the second insurgent attack inside Kabul in less than a week. On Wednesday, six Taliban militants attacked the Afghan intelligence agency in downtown Kabul, killing one guard and wounding dozens. Security forces killed all the attackers.