Security around Peshawar, the capital city of Khyber Pakhtunkhwa province in northwest Pakistan, is being beefed up as police and security brace for reprisal attacks, Home Secretary Akhtar Ali Shah said.
"Since this drone strike, we are waiting for a reaction," he said. "We know the reaction will be strong. We have strengthened security in Peshawar, especially at the entry points in to the city. We have extra security on patrol with sniffer dogs."
Strike hit Taliban stronghold
Three other people were killed in Friday's strike, Pakistani intelligence sources and tribal officials said.
They described the incident as a suspected U.S. drone strike in a remote area of Pakistan's North Waziristan region, a Taliban stronghold bordering Afghanistan and Khyber Pakhtunkhwa province.
One missile hit a compound, and another struck a car nearby, the Pakistani sources said.
This is not the first time Hakimullah Mehsud -- who took the reins of the Pakistan 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 in which he vowed attacks on major U.S. cities.
The fact that senior Pakistani government officials have commented so quickly on the news of his death this time adds credence to the reports.
Pakistan Taliban claimed Times Square plot
The Pakistan Taliban, which has long been conducting an insurgency against the Pakistani government, claimed responsibility for the December 2009 suicide bombing at the United States' Forward Operating Base Chapman in Khost, Afghanistan. Five CIA officers were among the seven U.S. citizens killed, and a member of Jordanian intelligence also died.
The U.S. Justice Department charged Hakimullah 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 Pakistan 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.
Hakimullah Mehsud's death could make progress in proposed peace talks between the Pakistani government and Pakistan Taliban more difficult.
A relatively young and charismatic leader, he held together a disparate group with different tribal and other allegiances.
There had reportedly been talks about him being involved in peace talks with Pakistan's government.
His killing may upset some elements within the Pakistan Taliban if they believe that the Pakistani government was involved.
The Pakistan Taliban could also pose an increased security threat if it splinters into smaller groups, which could be harder for security forces to detect.