A powerful blast triggered by a suicide bomber killed at least 44 people and injured nearly 100 others on Sunday at a rally of a hardline Islamic party in a restive tribal district of Pakistan's Khyber Pakhtunkhwa province bordering Afghanistan.
Saad Khan, the district emergency officer in the Bajaur region, said that Maulana Ziaullah Jan, JUI-F's local leader, was also killed in the blast, one of the worst in recent years.
Rescue workers said they feared the number of casualties would rise.
Television footage showed panic-stricken people gathering at the site following the blast as ambulances arrived to move the injured to hospitals.
Over 500 people were attending the convention when the blast occurred.
DIG police Malakand Range Nasir Mehmud Satti said the initial investigation revealed it was a suicide blast. However, evidence is being collected to determine the nature of the blast.
An official of the Bomb Disposal Unit said the initial investigation report confirmed it was a suicide blast in which 12 kg explosives were used.
The area was sealed and a search operation has been initiated, he said.
No group has yet claimed responsibility for the deadly attack, which came after a brief lull.
Prime Minister Shehbaz Sharif strongly condemned the blast at the JUI-F convention. He said terrorists targeted those who advocated the cause of Islam, the Holy Quran and Pakistan.
"Terrorists are enemies of Pakistan and they will be eliminated," he said in a statement released by the Prime Minister's Office.
Elements involved in the incident would be meted out with strict punishment, he said.
He also sought a report of the incident from Interior Minister Rana Sanaullah and the government of Khyber Pakhtunkhwa.
President Arif Alvi prayed for eternal peace for the departed souls and commiserated with the bereaved families. He also wished speedy recovery for the injured and emphasised the timely provision of medical assistance to them.
Interior Minister Rana Sanaullah vowed to bring the perpetrators of today's attack to justice.
"The cowardly acts of terrorists cannot dampen our spirits," he posted on X, the social media platform previously known as Twitter.
The JUI-F chief Maulana Fazlur Rehman demanded Prime Minister Sharif and the province's caretaker Chief Minister Azam Khan to investigate the incident.
He also urged the party workers to reach the hospital and donate blood.
"JUI workers should remain peaceful and federal and provincial governments should provide the best treatment to the injured," said Fazl.
Chief Minister Khan condemned the blast and sought a report from the district administration.
Police said that the injured have been shifted to a nearby hospital.
The condition of many injured people was stated to be critical.
JUI-F leader Hafiz Hamdullah said he was supposed to attend the convention today but could not because of some personal commitments.
"I strongly condemn the blast and want to give a message to the people behind it that this is not jihad but terrorism," the JUI-F leader said, adding that it was an attack on humanity and Bajaur.
He demanded that the blast should be probed, recalling that this was not the first that the JUI-F had been targeted.
"This has happened before...our workers have been targeted. We raised our voice over this in the Parliament but no action was taken."
Hamdullah also extended his condolences to grieving families and urged the provincial government to provide the best medical facilities to the injured.
Caretaker Information minister of the province Jamal Feroze Shah said an emergency was declared in hospitals of Peshawar and Dir district.
The US extended its deepest condolences to the families and loved ones of those killed and injured in the suicide blast and vowed its support for Pakistan's efforts in combating terrorism.
"Such acts of terror have no place in a peaceful and democratic society. We stand in solidarity with the people of Pakistan during this difficult time," the US embassy in Islamabad said in a statement.
"We reiterate our commitment to supporting Pakistan's efforts in combating terrorism and ensuring the safety and security of its citizens," it added.
Pakistan has witnessed a surge in terrorist attacks following the Afghan Taliban's return to power in August 2021 and called upon the interim rulers to take decisive actions against terrorists including the Tehrik-e Taliban Pakistan (TTP) responsible for cross-border attacks.
Meanwhile, Zabihullah Mujahid, a spokesman for the Taliban government in Afghanistan, has condemned the attack. TTP spokesman Khalid Khurrasani condemned the blast.
In November last year, the TTP called off an indefinite ceasefire agreed with the federal government and ordered its militants to carry out attacks on Pakistan's security forces.
On January 30, a Pakistan Taliban suicide bomber blew himself up during the afternoon prayers in a mosque in Peshawar, killing 101 people and injuring more than 200 others.
In February, heavily-armed TTP militants stormed the Karachi Police chief's office in Pakistan's most populous city, sparking gunfire that killed three rebels and four others, including two police constables.
The TTP was set up as an umbrella group of several militant outfits in 2007.
The outfit, which is believed to be close to Al-Qaeda, has been blamed for several deadly attacks across Pakistan, including an attack on army headquarters in 2009, assaults on military bases, and the 2008 bombing of the Marriott Hotel in Islamabad.
The TTP has also orchestrated the heinous Army Public School attack in Peshawar in 2014, in which over 130 students were killed.