According to public health officials 18 people, most of them civilians, were wounded in the attack against the Kabul traffic police headquarters that began with a suicide car bombing.
Mohammad Ayoub Salangi, the Kabul police chief said two attackers, armed with assault rifles and suicide vests were shot dead as they tried to enter the five-storey building and "one or two" other gunmen were fighting back.
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"Two attackers are killed by our police. One or two others are inside the building and fighting back. We have taken most of the building and we will clear the building very soon," Salangi told AFP from the scene in west Kabul.
Sediq Sediqqi, an interior ministry spokesman, gave a similar account and the Kabul CID chief, Mohammad Zahir, told local television that four police officers were slightly wounded in the attack.
According to witnesses a large pall of smoke was rising from the police building and sporadic gunfire and explosions, likely hand grenades, could still be heard.
An AFP photographer said Norwegian soldiers fired at the police building.
NATO's International Security Assistance Force (ISAF) confirmed its participation in the operation but insisted it was small.
"We do have a very small number of people assisting the Afghan security forces officials in the scene. It's primarily an advising role and absolutely the Afghan officials are in the lead," an ISAF spokesman told AFP.
He refused to give further details.
A local resident told AFP the attack started with a massive explosion that shattered the windows of nearby homes.
He said the initial explosion "very very big -- it was massive", and was followed by several other explosions and gunfire.
"There are firefighter trucks, ambulances and police all over the place. The gunfire comes from that direction and the building's top floors are on fire," he said.
Taliban insurgents, who are waging an 11-year war against the Western-backed government of President Hamid Karzai, claimed credit for the attack, which it said began at 5:00 am (0030 GMT).
"A large number of fedayeen (suicide bombers) entered a building in Dehmazang and are attacking an American training centre, a police centre and other military centres and have caused heavy casualties on the enemy," a Taliban spokesman said.
There is no US or NATO-run training facility in the area and the Taliban are known to exaggerate when claiming attacks.
Monday's attack comes less than a week after a squad of suicide bombers attacked the Afghan intelligence agency headquarters in Kabul, killing at least one guard and wounding dozens of civilians.
All six attackers were killed in the brazen attack on the National Directorate of Security (NDS), also claimed by the Taliban.
Afghan police and other security forces are increasingly targets of Taliban attacks as they take a bigger role in the battle against the insurgents before NATO withdraws the bulk of its 100,000 combat troops by the end of 2014.
Despite claims by the US-led NATO force that the insurgency has been weakened, Kabul is regularly attacked.
The Taliban also remain active in their traditional strongholds in the south and east of the country, and there are widespread fears of a new multi-factional civil war once international troops leave.
