ISLAMABAD, Pakistan -- Unidentified gunmen kidnapped a son of former Prime Minister Yousaf Raza Gilani on Thursday, officials said, throwing an already violence-ridden election campaign into more tumult.
The motive behind the kidnapping remained unclear late Thursday night, but suspicion focused on the Pakistani Taliban and banned sectarian militant groups. Taliban militants have issued several threats to political candidates, especially those belonging to liberal and secular parties, and have targeted political rallies with suicide and remote-controlled bombings.
The kidnapping came just two days after a leading candidate in the race, Imran Khan, a former cricket star, fell from a mechanical lift during a campaign rally, leaving him with back fractures, deep cuts and widespread sympathy, and changing the dynamics of the race. Pakistan's Taliban has threatened to disrupt the voting on Saturday by carrying out suicide bombings.
In Thursday's abduction, one of the former prime minister's sons, Ali Haider Gilani, believed to be in his mid-20s, was campaigning in a suburb of Multan, the family's power base. He is a candidate for the Punjab provincial assembly.
According to initial reports by local media outlets, Mr. Gilani had just stepped out of a house in the Farrukh Town neighborhood when he was attacked by a group of unidentified gunmen on a motorcycle and in a Honda automobile. They opened fire on him and his supporters, and Mr. Gilani's personal secretary was shot and killed.
It remained unclear if Mr. Gilani himself was shot. Some witnesses told reporters that his clothes were bloodstained as he was dragged by the kidnappers into their vehicle.
Two of Mr. Gilani's brothers immediately arrived at the scene. Ali Musa Gilani, who is running for a seat in Parliament against former Foreign Minister Shah Mehmood Qureshi, warned that unless his brother was set free by the evening, he would not allow voting to be held in his election district.
Sobbing, Ali Musa Gilani said, "I want my brother back."
Abdul Qadir Gilani, the eldest brother, who is also running for a seat in Parliament, criticized a decision by the country's election commission and Supreme Court to withdraw security assistance for candidates.
"We were not allowed to keep security guards," he said in an interview with private television networks. "The result is in front of you."
The men's father, Yousaf Raza Gilani, urged party workers in the country to continue with their campaigns.
"Our protest will continue," he said, speaking to reporters in Multan. "Those who want to disrupt the elections can be behind the kidnapping," he said, in an oblique reference to the Taliban.
Thursday was the last day of campaigning for the election -- a day longer than was widely believed at the start because of a misunderstanding over whether a 48-hour blackout period before the vote started from when polls were to open or from when they would close.
Attacks by militants during the election season have hobbled the ability of several parties to effectively campaign. The Awami National Party, which had earlier ruled the restive Khyber-Pakhtunkhwa Province, has suffered the most violence.
The security threats forced leaders of the Pakistan People's Party to remain low-key and abstain from most public appearances. Bilawal Bhutto Zardari, chairman of the Pakistan People's Party, has not appeared at any major public gathering, instead using video messages to speak to his supporters.
"The kidnapping is likely to demoralize the Pakistan People's Party leadership and supporters alike," Raza Rumi, a political analyst, said in an interview.
"Thus far, they had adopted the strategy of minimum risk to the top leadership," he said, "but now the family of the former prime minister has been targeted. This does not augur well for the democratic transition.
"It also reflects that lawlessness and nonstate actors are gaining more and more power and voice in Pakistan."
Correction: May 9, 2013, Thursday
This article has been revised to reflect the following correction: An earlier version of this article misstated the given name of the eldest Gilani brother and misspelled his middle name. He is Abdul Qadir Gilani, not Ali Qadri Gilani.
Correction: May 9, 2013, Thursday
This article has been revised to reflect the following correction: An earlier version of a headline with this article wrongly identified the victim of the abduction in Pakistan. A son of a former prime minister was abducted, not the former prime minister himself.
This article originally appeared in The New York Times.