Gunmen Storm Afghan Security Buildings

Two suicide bombers simultaneous attacked the headquarters of Afghanistan's Intelligence Agency (NDS) and its counternarcotics building in the eastern city of Khost Thursday morning, reported CBS News' Fazul Rahim.

The bomb blasts were followed by a group of armed men in military uniform storming the NDS building, according to an employee of a security firm which provides protection for non-governmental organizations and NATO coalition convoys in the region.

A statement provided by a public affairs company on behalf of the U.S.-led military coaltion in Afghanistan said one Afghan police officer was killed in the attack and three NDS workers were wounded.

The three wounded were taken to an International Security Assistance Force hospital for treatment, according to the statement, sent to CBSNews.com by the U.S. military command in Afghanistan.

The security employee told Rahim over the phone from Khost that he could not confirm any casualties, but he added that he could still hear gunfire and helicopters hovering over the area.

The statement, written by TF Currahee Public Affairs, said the attack involved "insurgents... using a vehicle-borne IED in conjunction with a suicide bomber wearing Afghan National Army clothing."

"Another potential suicide bomber wearing ANA clothing was identified fleeing from the scene," the statement said.

Khost's chief of police declined to comment on the attack, promising to get back to CBS News as soon as the ongoing gun battle around the NDS building was brought to a conclusion.

There is a strong U.S. troop presence in eastern Afghanistan, but it was unclear whether American or NATO coalition forces had arrived to support their Afghan counterparts in Khost.

Most of the attacks which have plagued Afghanistan this year have been less brazen, involving only a suicide or remotely detonated bomb, or kidnapping attempts. Thursday's strike, using commando-style militants, was reminiscent of a siege in January on the Serena Hotel in Kabul.

In that attack at least four militants, carrying assault rifles, grenades and other weapons, stormed the hotel and killed seven people. One of the assailants was captured. The Taliban claimed responsibility for the attack.

The strike in Khost comes one week after a group of about 10 well-armed, well-trained gunmen stormed the Indian city of Mumbai, taking over two luxury hotels and a Jewish center in the country's financial capital for 62 hours and leaving 171 people dead.

Intelligence officials have largely pinned blame for that attack on the Lashkar-e-Taiba militant group, based in Pakistan.