Story highlights Pakistani Taliban leader Hakimullah Mehsud killed in drone strike, officials say

Sources: Three other people killed in strike in northwestern Pakistan

Gunmen also opened fire on a vehicle, killing six

Police suspect it was a case of sectarian violence

Pakistani Taliban leader Hakimullah Mehsud -- once charged by the United States for his alleged involvement in a deadly 2009 attack on a U.S. military base in Afghanistan -- was killed in a drone strike in northwestern Pakistan on Friday, senior U.S. and Pakistani officials told CNN.

Three other people were killed in the strike, Pakistani intelligence sources and tribal officials said, describing the incident as a suspected U.S. drone strike in a remote area of Pakistan's Waziristan region, a Taliban stronghold bordering Afghanistan.

One missile hit a compound, and another struck a car nearby, the Pakistani sources said.

The government of Pakistan issued a statement through its foreign ministry saying it "strongly condems the U.S. drone strike" in Waziristan. The statement made no mention of Mehsud, and it was not clear whether the ministry knew of reports that he had been killed when the statement was released.

"The Government of Pakistan has consistently maintained that drone strikes are counter-productive, entail loss of innocent civilian lives and have human rights and humanitarian implications," the statement said.

Mehsud was buried, though the body was unrecognizable, Taliban sources said. The organization was scheduled to meet Saturday to pick a new leader, the sources said.

This is not the first time Mehsud -- who took the reins of the Pakistani Taliban in 2009 -- has been reported killed after a drone strike. In February 2010, multiple sources said he had died after being hit in a drone strike in Pakistan a month earlier.

But reports that he was alive surfaced in April of that year, and in May 2010 he appeared in a video vowing attacks on major U.S. cities.

The Pakistani Taliban, which has long been conducting an insurgency against the Pakistani government, claimed responsibility for a December 2009 suicide bombing at the United States' Forward Operating Base Chapman in Khost, Afghanistan. The attack killed seven U.S. citizens, including five CIA officers, and a member of Jordanian intelligence.

The U.S. Justice Department charged Mehsud in the summer of 2010 for his alleged involvement in the attack, and U.S. officials offered a $5 million reward for information leading to his capture.

The group also claimed responsibility for a failed May 2010 attempt to detonate a car bomb in New York's Times Square. The following September, the U.S. State Department designated the Pakistani Taliban a foreign terrorist organization.

Mehsud took over from Baitullah Mehsud, a fellow clan member, in 2009 after the latter was killed in a U.S. drone strike.

Elsewhere Friday, armed militants killed six Shiite Muslims in Pakistan's volatile Balochistan province, an incident suspected to be "sectarian terrorism," police said.

A seventh person was injured.

Four gunmen on two motorcycles opened fire at a vehicle carrying seven Shiite Hazaras in Bolan district, police official Ghullam Hussain said.

The shooting was indiscriminate, Hussain said. Three of the victims died at the scene and three more on the way to the hospital.

"The incident seems to be a sectarian terrorism," he said.

The attackers sped away after the attack.

There has been no claim of responsibility.