Kabul Smoldering

Kabul police told the BBC that armed men attacked the airport of a five-story building under construction.

It is not known if there were casualties.

BBC reporter at the scene said police rapid reaction force to fight to regain control of the area.

All flights have been canceled in and out of Kabul International Airport, which is home to major NATO military base.

Witnesses reported the sound of explosions and gunfire coming from the airport shortly after dawn on Monday.

No group has so far said it carried out the attack.

"Gunmen entered a house being built in the west in Kabul and fighting with security forces," said Kabul police spokesman Hashmatullah Stanekzai.

"Their target is the Kabul airport and all the way to it is sealed," he added.

The BBC's David Loyn is close to the scene said the helicopters were circling the area and there are still occasional gunfire and explosions.

Embassy in Kabul diplomatic area quickly locked.

Reports said the U.S. embassy had heard the alarm and announced over the loudspeaker that the alarm is not a drill.

Alarm also sounded loud from the British Embassy.

Taliban announce "spring offensive" in April, said it would target foreign military bases and diplomatic area.

Last month, the Afghan security forces against Taliban insurgents for hours in central Kabul after a huge explosion rocked the city.

Most of the international troops are scheduled to leave Afghanistan by the end of 2014. Afghan forces will take responsibility for security across the country in the next few months, for the first time since 1992.