A huge terror bomb demolished a bridge about six miles from Kandahar Friday, killing as many as 15 people and leaving body parts strewn about the twisted, mangled shell of a passenger bus.

The only survivors were a 12-year-old boy and the bus driver.

The blast destroyed the Rambasi Bridge, deputy police chief Ustad Nazir Jan said. No one claimed responsibility, but Jan blamed Taliban and Al Qaeda fugitives.

"One hundred percent we are sure it was Taliban and Al Qaeda," he said. "We will get the proof."

Jan said he believed Afghan soldiers from a nearby army post were the target of the bombing. Troops from the unit are loyal to Kandahar Gov. Gul Agha Sherzai and patrol the area.

"We believe they were the target, but we are investigating," he said.

Nomads living in a nearby camp witnessed the explosion.

"I was with my two children and we heard this loud noise. I ran away from it but then we heard people screaming, we went to help," said Toori Ali.

"It is the worst thing I have ever seen. There were body parts and only a small child and the driver lived," he said, still shaking from the sight of the carnage.

The two survivors were driver Ahmad Zia, 26, and the 12-year-old boy, whose father and uncle died at the scene.

The two were taken to a hospital in the town of Mir Wais, where Zia described how the blast tore through the bus as he crossed the bridge about 9:30 a.m. after leaving the village of Mala Dost.

"When the explosion occurred, I heard cries. Then I lost consciousness," he said. "When I woke up, I saw myself on the hospital bed."

Zia said he thought 15 passengers died in the explosion, although officials earlier said it could be up to 18. The driver said he didn't know who placed the land mine or whether his bus was the intended target.

Zia suffered cuts and burns to the face. The injured boy was listed as being out of danger.

While the police said they were convinced the culprits were the Taliban and Al Qaeda. Jan, the deputy police chief, said guerrillas loyal to renegade rebel commander Gulbuddin Hekmatyar may also have been involved.

Afghan and U.S. authorities believe that Hekmatyar's men are aligned with Taliban and Al Qaeda remnants.

Several Afghan soldiers were killed in a similar explosion about two months ago in Kandahar. A bomb went off as their jeep crossed a busy road.

On Sept. 5, 2002, an assassination attempt was made on Afghan President Hamid Karzai in Kandahar. The authorities also blamed Taliban and Al Qaeda. The would-be assassin was killed by U.S. Special Forces guarding Karzai. Two bystanders also were killed.

The Associated Press contributed to this report.