Taliban insurgents targeted a government office in Kabul early Monday, engaging in a shootout with security forces.
A suicide bomber detonated his explosives at 5:30 am (0100 GMT) at the gate of the Traffic Department, breaching the security perimeter at the compound, Kabul police said.
"Following the suicide bombing, two or three assailants equipped with light and heavy weapons occupied the building," it said.
"There are no exact figures on causalities but primary reports indicate that 10 people, including six civilians, have been wounded."
The building is adjacent to the border police headquarters, which Taliban militants said was their prime target.
"The gun battle between attackers and security forces is ongoing and parts of Traffic Department have caught fire," police said.
The Taliban claimed responsibility for the attack.
"A large number of martyr-seeker mujahideen armed with suicide vests, rocket-propelled grenades and light weapons attacked this morning the centre of foreign special forces' trainers and some police and other centres, killing a number of Afghan police officers and foreign trainers," spokesman Zabihullah Mujahid Taliban said.