Afghan forces kill last of Kabul attackers

Updated at 4:18 a.m. Eastern.

The Afghan government says the two-day insurgent assault in the heart of Kabul has ended and all the attackers have been killed.

The Interior Ministry says the area around the building where attackers had been holed up is now safe.

The head of the police unit overseeing the operation says that the last six attackers were killed inside the building at a major traffic circle in the Afghan capital.

Abdul Ghafar Sayedzada says there are no remaining insurgents alive in the structure.

He says Afghan security forces are now on the roof of the building after a slow clearing operation that lasted into early morning Wednesday.

CBS News' Fazul Rahim reports that 11 people were killed in the two-day siege, including three police officers, and 19 more were injured, including eight police officers.

A total of nine Taliban militants were involved in the attacks; six in the building near the U.S. Embassy and three lone suicide bombers who targeted police facilities in different parts of the city.

The coordinated assaults — coming two days after the United States marked the 10th anniversary of the Sept. 11 terror attacks — carried an unsettling message to Western leaders and their Afghan allies about the resilience and reach of the Taliban network.

It was the third major attack in Kabul since late June, casting fresh doubts on the ability of Afghans to secure their own country as the U.S. and other foreign troops prepare to withdraw by the end of 2014.

However, U.S. Ambassador Ryan Crocker, who waited out the majority of the firefight in the U.S. Embassy's fortified tactical center, dismissed the handful of rockets which landed within the sprawling compound's walls as "harassment," rather than a serious show of force by Afghanistan's insurgents.

The American Embassy and NATO both said no staff were wounded.

She said the U.S. would assist Afghans injured in the attack.

The surge of violence was a stark reminder of the instability that continues to plague Afghanistan nearly a decade after the U.S. invasion that ousted the Taliban for harboring al Qaeda, which carried out the 9/11 plane hijackings.

Violence in the once-quiet capital has escalated in recent months.

On Aug. 18 Taliban suicide bombers stormed a British compound in an upscale Kabul neighborhood, killing eight people during an eight-hour firefight as two English language teachers and their bodyguard hid in a locked panic room. Those killed included five policemen, a municipal worker, a security and a New Zealand special forces soldier who was shot in the chest as he tried to free the hostages — who survived.

On June 29, nine insurgents wearing suicide vests stormed the Intercontinental Hotel armed with rifles and rocket launchers on the eve of a major conference on Afghan governance. They killed at least 12 people and held off NATO and Afghan forces for five hours, until U.S.-launched helicopter airstrikes killed the last insurgents hiding on the roof.