The motley-dressed militias that once prowled the streets of northern Afghanistan's main city were gone Friday, and a commander of a new government-backed security force claimed his men were in control.

The withdrawal of militias from volatile Mazar-e-Sharif was an important step in attempts by the interim national government of Hamid Karzai to exert authority across a country where local warlords still have substantial power.

Along with factional fighting, such as the two days of battles that killed more than 60 people last week in the eastern town of Gardez, Afghanistan's security also is threatened by remnants of the Taliban and the Al Qaeda network. The United States has continued to launch attacks against suspected holdouts.

At a news conference Friday in Islamabad, Pakistan, a reporter challenged Karzai about how long he would tolerate the "futile" attempts to find Al Qaeda leader Usama bin Laden. Karzai responded sharply.

"The war against terrorism is not over, ma'am," he said. "We will have to go look for them in their hide-outs, in their caves, wherever they are. The fight against terrorism will go to the very end of it."

Concern about civilian casualties in the continuing U.S. campaign has grown recently. Three people unconnected to Al Qaeda died in rocket strikes in Paktia province this week, said Ghulam Gilani, a son of regional faction leader Bacha Khan, citing reports of local residents.

It was not clear whether these reports referred to a U.S. missile strike on Monday in which a suspected high-ranking Al Qaeda figure was rumored to have died.

More than 50 U.S. soldiers were at the site to investigate, according to Air Force Gen. Richard Myers, chairman of the U.S. Joint Chiefs of Staff.

In Washington on Friday, Myers said planners of the strike were confident that enemy fighters were targeted.

"There were lots of discussions among Central Command and other folks on the target," Myers said. "It was concluded that it was a valid target, and it was struck."

Paktia's main town is Gardez, where the most serious factional fighting since the fall of the Taliban exploded last week. It pitted fighters allied with the Gardez shura, or council, against the forces of Bacha Khan, who wants to take his seat as governor of Paktia.

He was appointed to the post by Karzai's government but is adamantly opposed by the shura, who say he is bloodthirsty and unscrupulous. A delegation from Gardez went to Kabul, the capital, on Friday for talks aimed at ending the crisis; but no indication of a resolution emerged.

Bacha Khan's side was represented by his brother Amanullah Zadran, who is Afghanistan's minister of border and tribal affairs, said deputy borders minister Mirza Ali.

The militia withdrawal from Mazar-e-Sharif appeared to go smoothly, and the fighters who once walked the streets and rode in pickup trucks, carrying automatic weapons and grenade launchers, were absent.

Members of the security force created as part of the withdrawal accord all wear red insignia, distinguishing them from the militia who wore an assortment of camouflage and civilian clothes and imparting a sense of consistency that is lacking in most of Afghanistan.

Showali, a force commander who uses only one name, said more than half of the 600-member security force has been selected and is on patrol. He said the force should be at full strength in the next week.

"The city is in complete control of the security forces" and the patrols have orders to disarm any unauthorized gunmen in the city, Showali said.

"We hope this will be the first of many cities in the north to push out the militias and come under the control of security forces aligned with the central government," said Showali. "The people want peace."

Also Friday, workers labored to clear snow away from the Salang Tunnel, two days after an avalanche blocked the key link between northern and southern Afghanistan and killed five people.

The avalanche, which underscored the vulnerability of Afghanistan's primitive infrastructure, trapped about 500 people, many of whom spent more than a day is snow-stranded vehicles in temperatures that plunged to minus-40. Eighty-nine of them were treated for dehydration and frostbite and at least seven of them were seriously injured.

One of the victims, 22-year-old Basa Gul, recalled the ordeal as she lay in a Kabul hospital where she was being treated for frostbite on her legs and arms.

"We were very worried; we didn't know what would happen to us," Gul said of the hours that she spent huddled under blankets in her car with her 1-year-old daughter Gululai.

She escaped by walking two hours through waist-high snow to the nearest village.

In other developments:

• The United Nations health agency said Friday it is planning to fly in emergency medical supplies to Afghans cut off by heavy snow in Ghor province in west central Afghanistan.

• The International Organization for Migration said Friday it planned to close all 19 camps for displaced people around Mazar-e-Sharif because most of the people there are only pretending to be homeless.

Spokeswoman Niurka Pineiro said about 180,000 people have set up tents in the camps, even though they live only a few miles away, in the hope of receiving food.