Two air-to-ground missiles ripped through the sky before smashing into the house where a Taliban leader with close links to al Qaeda chief Osama bin Laden was thought to be hiding.
"There was a glittering flash of light and a prolonged roar," said Hameedullah Khan, one of the first on the scene of Monday's suspected US drone strike in the town of Dande Darpa Khel, near the Afghan border.
Two white drones circled the area for hours ahead of the attack that left 21 people dead, including women and children, residents told AFP. "We recovered 10 bodies, some were mutilated, some charred. We could not identify if the victims were locals or foreigners. But we could distinguish that children were among the dead," Khan said.
The reputed target of Monday's attack, veteran Taliban commander Jalaluddin Haqqani, was not among those killed, and the devastation left on the ground seems only to have strengthened the Taliban's influence on local civilians.
"After about an hour, the Taliban turned up," said Khan, who helped in the rescue work at Dande Darpa Khel. "They ringed a building and erected a tent (to treat casualties) nearby," the 35-year-old said.
"Then they recovered more bodies and wounded who were sent to hospital."
Washington says Pakistan's mountainous tribal regions have become a safe haven for fighters waging an insurgency against international troops based across the border. But the increasingly frequent missile attacks, for which the United States has not claimed responsibility, are straining Pakistan's relationship with its key ally.
Residents in Dande Darpa Khel say until recently, one drone would comb the region late at night or early in the morning. But now, two or three will fly together, around the clock.
"They keep on flying in our skies with full immunity and people are scared," said Abdus Khan, a 22-year-old student, adding that the prospect of further attacks may lead people to flee the area. The US believes that Bin Laden and his deputy, Ayman al-Zawahiri, are hiding in the tribal regions, but security officials say the increase in missile attacks is ineffective. "Pakistan's army is fully-fledged in crushing Taliban and al Qaeda fighters," a senior military official told AFP.
"The Americans must show patience and let us succeed in our strategy. When they launch unilateral strikes it is only counter-productive," he added. Riffat Hussain, head of peace and conflict studies at Islamabad's National Defence University, said the strikes were undermining the fight to combat militancy in the tribal belt.
"This is playing into the hands of the extremists, especially when civilian collateral damage is much higher than the actual damage the Americans think they are causing to militant outfits or sanctuaries," Hussain said.