At least 18 people were killed near the southern Afghan city of Kandahar on Friday when a bus hit a mine which police said had been planted by the al Qaeda network of Osama bin Laden . Witnesses who rushed to help the survivors described a scene of bloody carnage. Hours after the explosion, debris was still scattered over a large area and a three-foot-deep crater blasted out of the road. "It was around 8 a.m. (10:30 p.m. EST Thursday) when I heard a loud bang and rushed to the site where I saw people covered in blood," said Asadullah, a villager with blood specks on his shoes.

"I helped the driver and two other people who were wounded to the hospital. People were torn into pieces."

Mohammad Osmaan, who visited the local hospital, said the driver of the bus was injured and a young boy escaped with minor wounds and was later discharged. A third survivor died in hospital taking the death toll to 16, witnesses said.

But Kandahar provincial spokesman Khalid Pashtun later told Reuters that 18 people had died in the blast, which took place near Rambasa, some 12 miles south of Kandahar.

"It was not only a mine but a mortar shell was attached to it," Pashtun said.

Ustad Nazir Jan, police chief of Kandahar, said he suspected the al Qaeda network and renegade warlord Gulbuddin Hekmatyar of planting the device, but Pashtun did not agree:

"It is very difficult to say who was behind it. I guess it could be Taliban and Gulbuddin, because al Qaeda are now gone. They are finished."

AL QAEDA CLAIM DISPUTED

Rahimullah Yusufzai, a leading Afghan expert based in neighboring Pakistan, also doubted that al Qaeda were involved in the attack. He said remnants of the ousted Taliban regime, whose stronghold was in Kandahar, were more likely suspects.

He added that the Taliban may also have been behind a fierce battle earlier this week near Spin Boldak on the Afghan-Pakistan border, in which 18 rebels were killed as U.S. warplanes pounded their cave complex in the biggest Afghan battle in 10 months.

The U.S. military and local Afghan officials have said the group of up to 80 rebels was loyal to Hekmatyar.

Yusufzai said the escalation of attacks on U.S. and other targets in Afghanistan  in recent months was a sign that sometimes small extremist groups were becoming increasingly bold.

"It has been happening more and more frequently over the last few months," he told Reuters. "A year or so after U.S. military operations began, maybe the fear of the Americans is receding."

Between 7,000 and 8,000 U.S. troops are stationed in Afghanistan leading the hunt for members of the hard-line Islamic regime and the al Qaeda terror network blamed for the September 11, 2001 attacks on New York and Washington.

They have yet to find bin Laden or Taliban leader Mullah Omar, and hundreds of al Qaeda and Taliban fighters are believed to have fled Afghanistan into neighboring Pakistan where many are still hiding.

Friday's blast was the worst attack in Afghanistan since last September, when 26 people were killed and dozens injured in a huge car bomb in the capital, Kabul.

On the same day, President Hamid Karzai narrowly survived an assassination attempt in Kandahar, which he blamed on al Qaeda or the Taliban. The U.S. military has a base in Kandahar.

PHOTO CAPTION

A powerful explosion has killed at least 18 people near the southern Afghan city of Kandahar, authorities say.