The bloodshed began on Friday with a truck bomb that exploded in a heavily populated district and included an hours-long battle at a base used by U.S. special forces. It became the deadliest day in Kabul for years. The Islamist insurgents claimed responsibility for both the police academy attack and the battle at the U.S. special forces base, though not for the truck bomb.

The violence was a reminder of the difficulty of reviving a stalled peace process, conveying a no-compromise message from the Taliban following the late July revelation of Mullah Mohammad Omar's death and a dispute over the leadership of the insurgency. "The question is, who is sending the message?" said Thomas Ruttig of the Afghanistan Analysts Network.

The U.N. mission in Afghanistan said Friday was the most violent day since it began recording civilian casualties in 2009, with 355 civilians killed or injured. On Saturday, NATO-led coalition forces confirmed that one international force member and eight Afghan contractors had been killed in the attack on Camp Integrity, a base used by U.S. special forces near the airport.

The blast outside the base was powerful enough to flatten offices inside, wounding occupants who were airlifted by helicopter to military hospitals. "There was a big explosion at the gate ... (The gunfire) sounded like it came from two different sides," said a special forces member who was wounded when his office collapsed.

The initial blast caused by a suicide car bomb at the gate was followed by other explosions and a firefight that lasted a couple of hours, he said. "The helicopters went on for hours ... medevac-ing people out," a U.S. contractor at a camp nearby said.

A US spokesman for the NATO mission in Afghanistan said the Taliban had increasingly turned to high profile attacks. "The recent attacks in Kabul are consistent with this trend," said the spokesman, Brigadier General Wilson Shoffner.

Camp Integrity is run by U.S. security contractor Academi, which was known as Blackwater before being sold to investors. It said eight Afghans contracted to a local partner security firm were killed. It declined to comment further.

In Washington, the White House said National Security Advisor Susan Rice had spoken with Afghan President Ashraf Ghani by telephone to express U.S. condolences.

Latest News from World News Desk