Militants armed with machine guns and rocket-propelled grenades engaged in a firefight with security forces for several hours along the perimeter of Afghanistan’s main airport in Kabul on Monday, after an unsuccessful attempt to attack NATO’s airport headquarters, the army and police said.

At least five insurgents, of which at least two have died so far, fought security forces, AP reported, citing Kabul police. No casualties were reported among police or civilians, the report said.

The Taliban claimed responsibility for the attack, saying the militants were targeting NATO, AP reported.

All civilian air traffic in and out of the city's international airport, as well as roads leading to the airport, were closed following the attack.

A “duck and cover” warning was sounded in the U.S. embassy, while alarms were heard ringing loudly from the British embassy, and other embassies in the diplomatic area of Kabul were immediately locked down, BBC reported.

The ongoing attack is believed to be part of the Taliban’s “spring offensive,” announced in April, targeting foreign military facilities and diplomatic missions.

Kabul police said militants wearing bomb-laden vests had occupied two buildings under construction on the west side of the airport and began firing at the NATO-led military base. It remains unclear if the attack  inflicted any damage to facilities inside the airport.

“It first started with a big explosion which we think was a suicide attack. After that a gunbattle started,” Kabul police spokesman Hashmat Stanikzai told AP.

“Sometimes they are shooting from one building, sometimes from other. It is a residential area and the compound has been surrounded by Afghan security forces. The security forces surrounded the buildings and are being careful because it is a residential area.”

Gen. Murad Ali Murad, of the Afghan army, said sporadic shooting continued, while one of the buildings in which the attackers were hiding was surrounded.