An election candidate for Imran Khan's party was killed in a suicide bombing three days ahead of polling in Pakistan's general election.
Ikramullah Gandapur was fatally wounded along with his driver, while three companions were badly hurt when a 20lb bomb tore through his vehicle as he returning home from a political meeting.
The killing was claimed by Pakistan's Taliban and deepened fears of more attacks ahead of polling for the country's 106 million voters.
Mr Khan condemned the attack on his candidate who was standing for a seat in a provincial assembly in Khyber Pakhtunkhwa.
“ Saddened to learn that Ikram Gandapur succumbed to his injuries,” he said. “My prayers go to his family. May Allah give them the strength to bear this loss.”
Video images from the scene in the city of Dera Ismail Khan showed three bleeding and unconscious passengers inside a badly damaged black 4x4 vehicle.
Political violence claimed Mr Gandapur's brother Israrullah in 2013. The then provincial law minister was killed in a suicide attack on his home.
Pakistan's July 25 poll will see members elected for the country's lower house of parliament and four regional assemblies.
Police said Mr Gandapur, of Imran Khan's Pakistan Justice Movement (PTI) party had been warned about serious threats to his life and been provided with 11 policemen.
A police spokesman claimed he had not informed police about his Sunday political meeting.
The convoy of another election candidate, Akram Durrani, also came under fire in the northwestern town of Bannu, though no one was hurt.
Mr Durrani survived a suicide attack earlier this month that killed four people.
Violence in the campaign has sharply escalated in recent weeks after a relatively peaceful start.
Earlier this month, another provincial assembly candidate was killed in one of the worst terrorist attacks Pakistan has ever suffered.
A massive suicide bombing at a rally in Mastung in the south western province of Baluchistan province, killed Siraj Raisani along with 148 people.
Another bombing three days earlier in the northwestern city of Peshawar, had killed another provincial candidate and 20 others.
Counter terrorism officials have warned several party leaders their lives are under threat.
Pakistan's army has said it will deploy more than 370,000 troops on polling day – around five times as many as for the 2013 poll when the country's security was generally considered to be much worse.
The enormous mobilisation will include troops placed inside and outside polling stations.
Mr Khan's party appears to have surged in popularity in recent months, leaving the election as a two horse race with the Pakistan Muslim League (PML-N) party of jailed former prime Minister Nawaz Sharif.
On Sunday, Pakistan's top court said it had begun reviewing a judges allegations that the country's spy agencies were influencing judicial proceedings. The military also called for an investigation into the judges comments.
Sharif, who is in prison with his daughter Maryam after the pair were jailed by an anti-corruption court, has accused the military of leaning on the judiciary to pursue investigations against his PML-N party.
Shaukat Aziz Siddiqui, an Islamabad Hight Court Judge had accused the country's premier spy agency, the Inter Services Intelligence (ISI), of interfering in legal cases.
"The ISI is fully involved in trying to manipulate the judicial proceedings," Mr Siddiqui said told a bar association speech on Saturday.
He said the agency had told the court not to release Sharif and his daughter Maryam until after the elections.