A car bomber slaughtered 16 people, including two American soldiers, in a massive explosion Friday outside the U.S. Embassy, the deadliest suicide attack in the Afghan capital since U.S.-led forces toppled the Taliban after the Sept. 11, 2001, attacks.

Meanwhile, NATO troops killed 20 to 30 Taliban in airstrikes and artillery barrages in southern Afghanistan during Operation Medusa. The latest deaths take the toll of insurgents killed according to NATO to at least 290 since the operation began Sept. 2.

The U.S. military blamed "Taliban extremists" for the morning blast, which spewed body parts and pieces of U.S. military uniforms across a major road and into trees that were set alight by the explosion -- part of the worst spate of violence in Afghanistan since the collapse of the hard-line Islamic regime. More than 20 Taliban were killed Friday in an ongoing NATO operation in the south.

The attack shattered what had been a typically peaceful Muslim sabbath in the war-ravaged capital and revealed the lingering vulnerability for foreign troops, local forces and Afghan civilians to terrorist attacks almost five years after the Taliban regime fell and a pro-American government was installed.

The explosion went off at 10:20 a.m. just 50 meters (yards) from the landmark Massood Square, which leads to the main gate of the heavily fortified American Embassy compound. It tore a 2-meter (6-foot) -wide crater into the road and left body parts, Muslim prayer caps, floppy khaki-colored military hats and shoes scattered over a wide area.

Witness Najibullah Faizi saw a blue Toyota Corolla driven by a young heavily set man speed past another car on the inside lane before ramming one of two U.S. Humvees in a convoy.

"I fell to the ground after the blast. American soldiers started shooting at another car nearby. There was smoke and flames everywhere," Faizi, 25, said.

The blast sent a plume of brown smoke spiraling hundreds of meters (feet) into the sky and tore apart one of the Humvees, blowing it onto what had been its roof and turning it into twisted, flaming hulk of metal.

All that remained of the bomb-packed car was its front end, which was covered in flames some 20 meters (yards) away. A foot and ankle -- apparently the attacker's -- was thrown 30 meters (yards) further.

Angry residents condemned the terrorist attack, which took place as many Afghans were commemorating the Sept. 9, 2001, assassination of revered anti-Taliban mujahedeen commander Ahmad Shah Massood, and demanded militants end attacks in heavily populated areas.

"This is a cowardly action that terrorists always take. They don't care if it is a residential area, government area or military area," said resident Mohammed Hayder Nangahari.

Pharmacist Nawid Paidar, 31, said the killing of children, men and women in terrorist attacks was inhumane and he blamed militants crossing from Pakistan for the latest bombing.

"The Americans should execute those who organize terrorist attacks as a lesson to others," said Paidar as he removed pieces of wood and other debris from his storefront that was ravaged by the blast.

Pakistani President Gen. Pervez Musharraf visited Kabul this week for talks with Afghan counterpart Hamid Karzai. The two leaders, both key allies of U.S. forces hunting Osama bin Laden along their vast, tribal-dominated frontier, vowed to improve cooperation to defeat the "common enemy" of terrorism.

The blast's force shattered every window in a five story Soviet-era apartment block facing the bomb scene, spraying shards of glass over children eating their breakfasts and women cleaning their cramped homes. Restaurants and businesses on the other side of the road also had windows and doors blown in.

An Associated Press reporter at the scene saw the bodies of two American soldiers lying meters (yards) from their burning vehicle. U.S. troops stood guard around the bodies, one of whom was slumped in the gutter, the other covered by a plastic sheet. The U.S. military initially said two other soldiers were also wounded, but later revised it down to one.

Sixteen people in all were killed and 29 wounded, said Ali Shah Paktiawal, criminal director of the Kabul police. The bomber also died.

Among the victims was Bibi Omayra, aged in her 70s, who had been sitting with her granddaughter in a small yard outside the apartment building when the car bomb exploded, spraying shrapnel over a 50 meter (yard) radius.

"My mother just went to the park for some fresh air with my daughter when the explosion happened," said the woman's son, Farid Wahidi, 40. "Shrapnel hit her in the chest and killed her."

Taliban holdouts behind this war-ravaged country's deadliest upswing in violence since the hard-line regime's fall have been turning to Iraqi-style tactics -- including increasing numbers of suicide bombings -- to try derail Karzai's U.S.-backed government.

"Today's heinous act of terrorism is against the values of Islam and humanity," the Afghan leader said in a statement.

Top U.S. operational commander Maj. Gen. Benjamin Freakley condemned the latest killings of American troops "by these Taliban extremists who care nothing about human decency or life."

Some 20,000 NATO soldiers and a similar number of U.S. forces are trying to crush the emboldened Taliban insurgency. The heaviest fighting takes place across vast desert plains in southern Helmand and Kandahar provinces, also center of the country's massive opium trade.

"The fighting is extraordinarily intense. The intensity and ferocity of the fighting is far greater than in Iraq on a daily basis," Brig. Ed Butler, the commander of British Forces in Afghanistan, told British ITV news.

He echoed NATO commander Gen. James L. Jones' call Thursday for at least 2,000 more troops. Jones, who said the next few weeks would be decisive in the fight against militants, is in Poland pressing officials from the 26 NATO member states for more soldiers and air support.

NATO spokesman Lt. Col. Nick Grant-Thorold said 20 to 30 Taliban were killed in airstrikes and artillery barrages early Friday in Kandahar province's Panjwayi district during the anti-Taliban Operation Medusa.

Another NATO spokesman, Maj. Scott Lundy, said hundreds of Taliban insurgents are believed holed up in and around Panjwayi, west of Kandahar city.

Four Italian soldiers in western Farah province were wounded -- one seriously -- Friday by a roadside bombing near the town of Ganjabad, NATO and the Italian Defense Ministry said.

In the southern city of Kandahar, a would-be suicide attacker killed only himself when his bomb-packed car exploded prematurely, police said.

About 70 Taliban fighters firing rockets attacked a district government headquarters at Chaki Wardak, in the central province of Wardak, early Friday, before police repelled them, police said. Witnesses said eight Taliban were killed, but police retrieved no bodies.

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CountryWatch: Afghanistan