DERA ISMAIL KHAN, Pakistan, (AP) – The Taliban are unusually angry about the latest suspected U.S. missile strike in Pakistan, a sign a top militant may have died in the attack, officials and residents said Sunday amid reports the death toll rose by two to 24.

Elsewhere in Pakistan’s northwest, an official said some 15,000 Afghans had left a tribal region the military is trying to wrest from insurgents, but that tens of thousands more had yet to meet a government ultimatum to get out by Sunday.

The U.S. has ramped up cross-border strikes on alleged al-Qaeda and Taliban targets along Pakistan’s side of the border with Afghanistan, straining the two nations’ anti-terror alliance.

The U.S. says pockets of Pakistan’s border region, especially in its semi-autonomous tribal areas, are bases for militants attacking American and NATO forces in Afghanistan. It has pushed nuclear-armed Pakistan to eliminate the safe havens.

The frontier region is believed to be a possible hiding place for al-Qaeda leader Osama bin Laden and his deputy Ayman al-Zawahri, and several Arab militants were said to be among the dead in Friday’s strike in North Waziristan tribal region.

Two Pakistani intelligence officials said that over the weekend two people wounded in the attack died at a hospital in Miran Shah, the main town in North Waziristan. The officials sought anonymity because they were not authorized to speak to media.

Based on information from informants and agents in the field, the intelligence officials said the Taliban appeared extra-perturbed over the latest strike. The anger was a signal that a senior militant may have been killed, but that has yet to be confirmed, the officials said.

The insurgents were moving aggressively in the area while using harsh language against locals, including calling them “saleable commodities” — a reference to people serving as government spies, the officials said.

Two local residents said Taliban fighters had warned people not to discuss the strike, including with the media, or to try inspecting the rubble at the site. The residents asked not to be named for fear of Taliban retaliation.

The strike in Mohammadkhel appeared to be the deadliest of 11 reported cross-border operations by U.S.-led forces since Aug. 20. The area is a stronghold of Jalaluddin Haqqani, a veteran Taliban commander regarded by the U.S. as one of its most dangerous foes.

The U.S. rarely acknowledges such attacks, 1st Lt. Nathan Perry, a spokesman for the U.S.-led coalition in Afghanistan, said he had “no information to give” about the reported attacks. He did not deny U.S. involvement.

The information is nearly impossible to verify independently because of the remote, dangerous nature of the areas.

Taliban spokesmen could not immediately be reached for comment Sunday. Neither could Pakistani government and military spokesmen.

Earlier, however, Pakistan army spokesman Maj. Gen. Athar Abbas said initial reports indicated that 20 or more people were killed. He said there was “speculation” that many were foreign militants, but cautioned that the army was still awaiting a detailed report.

Pakistan’s military and civilian leaders have complained that the attacks violate the country’s sovereignty, kill civilians and anger the local population, making it harder to crack down on the militants.

Extremists based in the border region are blamed for rising attacks in Pakistan, including the Sept. 20 truck bombing of the Marriott Hotel in Islamabad that killed more than 50 people.

The prime minister’s office announced Saturday that a special joint session of parliament would be held Wednesday so intelligence agencies could privately brief lawmakers about the militant threat facing the country.

Ahsan Iqbal, a top member of the lead opposition party, welcomed the joint session saying it could help clarify U.S. motives in launching operations in Pakistan.

“Before this, America did a very big war operation in Iraq,” he told GEO television. “That time, too, America said that there was an intrusion in Iraq from Syria and Iran but we saw nowhere that America could have violated the borders of Syria or Iran.”

The Pakistani military has been carrying out its own operations against insurgents in the northwest, most notably in Bajur, a tribal region Abbas called a “mega-sanctuary” for militants.

The U.S. has praised the military offensive in Bajur, but it has also led to a major humanitarian crisis. Hundreds of thousands of civilians have been displaced by the fighting.

Many are in refugee camps in Pakistan, but some 20,000 Pakistanis have sought crossed the border into eastern Afghanistan, according to the United Nations.

Meanwhile, a three-day ultimatum from the government for Afghans living illegally in Bajur to leave was due to expire later Sunday. But of an estimated 80,000 Afghans, only about 15,000 had left, said Abdul Haseeb, a local government official.

He said the exodus appeared to be continuing, and that “the administration may be lenient and give them another couple of days.”

“They are leaving with all their belongings and cattles and hopefully most of them will leave in another two days, but if they don’t there would be a massive crackdown,” Haseeb said.

It was unclear, however, whether the Afghans were all heading back across the porous, disputed border to Afghanistan or simply going to other parts of Pakistan.

Ghulam Jan, an Afghan who said he came to Pakistan years before as a child with his parents, was preparing to head across the border to Afghanistan’s Kunar province with 13 members of his family, a cow and two calves.

“My parents are buried here. I consider this my homeland, but suddenly we are being uprooted to build our home anew in a hostile situation,” he said.