ISLAMABAD — Bombings targeted a Pakistani police station and set a NATO fuel convoy ablaze Sunday, killing 16 cadets in the northwest's Swat Valley and threatening the supply line to international forces in Afghanistan in a separate attack near the border.

The two blasts hours apart and hundreds of miles from each other came as Pakistani officials said the Taliban were ramping up strikes to avenge recent setbacks, including the loss of territory to the military and the death of their top leader in a CIA missile strike near the Afghan border.
(See TIME's photos: Pakistan beneath the surface)

Pakistan's military has in recent months intensified its fight against the al-Qaeda-linked extremists, who threaten stability in the nuclear-armed nation and are suspected of helping plot attacks against U.S. and NATO troops across the border in Afghanistan.

At least 16 cadets died Sunday after a suicide bomber sneaked into the courtyard where they were training in Swat's main town of Mingora and detonated his explosives, local government official Atifur Rehman said. It was the deadliest attack since an army offensive ended Taliban rule there.

Investigators later sifted through the blackened wreckage in the courtyard littered with body parts, shredded uniforms and police berets.

Authorities were looking into reports the attacker may have donned a uniform and slipped into the station posing as one of the dozens of recruits, Deputy Inspector General Idrees Khan of the district police said.

"We are investigating whether the bomber climbed over the wall of the police station, or whether he was already present among the police cadets," Khan said. He blamed the attack on a decision to relax a daily curfew in the area for the Muslim holy month of Ramadan, and police quickly blocked off roads and ordered residents back indoors.

The army's offensive to take back the area was its largest in years after periodic peace deals with the militants. The Taliban's takeover of parts of Swat, a former tourist enclave, about two years ago became a symbol of their expansion in the mostly Muslim country of 175 million.

Pakistan's army says it is restoring order to the valley and surrounding areas, but Sunday's attack indicated that while the Taliban may no longer be able to impose their harsh interpretation of Islam there, life is far from normal for the hundreds of thousands who are now returning after fleeing the army's fierce three months of fighting to wrest back control.

Provincial minister Bashir Ahmed Bilour blamed the Taliban for the suicide attack and said Pakistanis must be "mentally prepared" for more bombings until the Taliban are crushed.

The Pakistani Taliban have vowed revenge after the loss of Swat and the death of their top leader, Baitullah Mehsud, in a CIA missile strike Aug. 5 further west near the Afghan border. At least 40 U.S. drones have fired missiles into Pakistan's lawless border areas, targeting militant leaders believed to threaten the war effort in Afghanistan.

The other blast Sunday ripped through a line of trucks ferrying fuel to NATO troops in Afghanistan, setting several oil tankers ablaze at a backed-up border crossing in southwestern Baluchistan province, police said.

The blast appeared to be the second terrorist attack in a week to target a border crossing.

Local police chief Hasan Sardar said flames and smoke were billowing into the sky Sunday night as authorities struggled to control the blaze near the Chaman border crossing in Baluchistan province in Pakistan's southwest.

"It was a big explosion under one of the oil tankers that caused other vehicles to catch fire. The fire is spreading," Sardar told The Associated Press by phone.

"We are at the moment trying our best to control the blaze. We are not sure whether there is any human loss," he said. "It is just panic everywhere there."

Police officer Gul Mohammad said from the scene that a bomb was suspected. He said security officials had earlier found and defused another explosive device lying near one of the NATO tankers.

"This was another bomb, which we could not find in our earlier search, that exploded," Mohammad told the AP.

An eyewitness, Haji Mahmood, said he saw some men in a car and two on a motorcycle spraying the vehicles with a volley of bullets before the blast.

"The two men abandoned their motorcycle and escaped in the car," Mahmood said.

Chaman is one of two main crossing points for supplies for American and NATO troops fighting the Taliban in Afghanistan. The foreign troops get about 75 percent of their supplies through Pakistan.

Some 1,000 trucks, many of them NATO tankers, were backed up on the road leading to the border because the Chaman crossing had been closed for two days in a dispute between customs officials over fruit inspections, police officer Abdul Rauf said. Afghan officials closed the border on Saturday in retaliation for lengthy inspections by Pakistani customs that were holding up Afghan trucks carrying grapes and pomegranates, he said.

Rauf said that he heard the explosion and saw at least three oil tankers, two container trucks and two dump trucks on fire.

Another suicide bombing Thursday killed at least 19 guards further north at the Torkham border crossing, the other main route into Afghanistan and gateway to the famed Khyber Pass.