DERA ISMAIL KHAN, Pakistan — The Pakistani Taliban confirmed the death of their leader in a U.S. drone strike Saturday, a day after he was killed, as the group’s leadership council met to begin the process of choosing a successor.

The death of Hakimullah Mehsud, a ruthless leader known for attacking a CIA base in Afghanistan and a bloody campaign that killed thousands of Pakistani civilians and members of the security forces, is a heavy blow for the militant group.

The drone strike came as the Pakistan government tries to negotiate a peace agreement with the Tehreek-e-Taliban, as the militant group Mehsud headed was formally called. Already the strike threatened to worsen U.S.-Pakistan relations as some Pakistani politicians called the strike an attempt to sabotage the peace talks.

“We are proud of the martyrdom of Hakimullah Mehsud,” Azam Tariq, the Pakistani Taliban spokesman in the South Waziristan tribal area, said in the first official confirmation of the leader’s death. “We will continue our activities.”

The Taliban’s Shura Council, a group of commanders representing various wings of the group, gathered at an undisclosed location Saturday in the North Waziristan tribal area, intelligence officials and militant commander said. That’s the same region where a U.S. drone strike killed Mehsud on Friday.

The Shura will continue to meet for a few days before it makes a decision, Tariq, the Taliban spokesman, told The Associated Press by telephone from an undisclosed location.

Two candidates to succeed Mehsud are Mullah Fazlullah, the Pakistani Taliban chief for the northwest Swat Valley, and Khan Sayed, the leader in the South Waziristan tribal area. The information came from three Pakistani intelligence officials and five Taliban commanders interviewed by phone.

Omar Khalid Khurasani, who heads the group’s wing in the Mohmand tribal area, is also in the running, two of the militant commanders said. He was not believed to be a strong candidate.

Mehsud and the other four militants killed in the strike were buried Saturday at an undisclosed location, the Taliban commanders said.

Drones still flew over North Waziristan on Saturday. Witnesses in the towns of Mir Ali and Miran Shah reported Mehsud’s supporters fired at them in anger.

Mehsud was killed in a village outside Miran Shah when multiple missiles slammed into a compound just after a vehicle carrying the militant commander arrived. The other militants killed were identified as Mehsud’s cousin, uncle and one of his guards. The identity of the fourth militant is not yet known.

Mehsud gained a reputation as a merciless planner of suicide attacks in Pakistan. After taking over as the Pakistani Taliban’s leader, he tried to internationalize the group’s focus.