Explosions and gunfire rocked central Kabul Friday as the Taliban launched a major attack close to an Afghan intelligence facility and the headquarters of a government force that protects foreign firms.
Smoke rose from the site of at least one suicide car blast that started the coordinated assault before commando security forces began an operation to clear several militant gunmen who took up positions in nearby buildings.
The attack comes a week after another suicide car bomb in Kabul targeted a foreign military convoy killing 15 people, including five Americans, in the deadliest attack in the Afghan capital for nearly a year.
The Taliban announced their annual "spring offensive" on April 27, opening a crucial period as local security forces take the lead in the fight against the insurgents.
The blasts hit the centre of Kabul at about 4:00 pm (1130 GMT) on Friday, the weekly holiday in Afghanistan, and gunfire was continuing sporadically two hours later.
Security forces killed two of the gunmen who were firing and throwing grenades from a building, interior ministry spokesman Sediq Sediqqi told the Tolo news channel, without saying how many attackers remained.
Kabul police spokesman Hashmat Stanikzai told AFP the initial explosion was close to a hospital run by the NDS intelligence agency and the headquarters of the Afghan Public Protection Force (APPF), which provides security for clients including international firms, supply convoys and aid groups.
"Six or seven attackers were involved, with one car suicide bomb at the start. Other attackers entered buildings and are fighting back," Stanikzai said.
The exact target of the attack was unclear, but the International Organization for Migration and the United Nations Assistance Mission in Afghanistan (UNAMA) have premises close by.
Taliban spokesman Zabiullah Mujahid told AFP that his group was responsible and that the main target was a guesthouse allegedly used by NDS and US intelligence staff, though the claim was impossible to verify.
"A group of mujahideen armed with heavy and light weapons took position in a building and are firing on several targets," he said.
"The main target was a guesthouse where foreigners, including members of CIA who train members of the Afghan spy agency stay."
Jawed Kazem, a local shopkeeper, said: "I was sitting in my shop when the explosion happened. It was a big explosion which threw me off my chair, minutes later another explosion happened.
"Smoke is rising and gunfire is continuing," he told AFP.
The suicide bombing on the NATO convoy on May 16 was the first major attack in Kabul since March 9, when a bomber on a bicycle killed nine people outside the defence ministry during a visit by US Defense Secretary Chuck Hagel.
The attacks further underline the capital's vulnerability to militant assaults as 100,000 NATO troops gradually withdraw from Afghanistan ahead of the end of international combat operations next year.
Local forces are increasingly coming under attack from the Taliban as they take over from foreign forces.
Six members of the APPF were killed on Tuesday in a roadside bombing in western Afghanistan as they travelled to a hydroelectric dam that is under protection from insurgent attack.
More than 11 years after the Taliban regime was ousted in 2001, efforts to seek a political settlement ending the violence have so far made little progress, but pressure is growing ahead of the NATO withdrawal.