Story highlights Imran Khan and his guards tumbled about 20 feet near a rally stage

Khan is one of two frontrunners for prime minister

Saturday's election will mark Pakistan's first democratic transition of power

The run-up to Pakistan's elections has been beset by violence, particularly by the Pakistani Taliban

Famed politician and Pakistani cricket star Imran Khan suffered spinal fractures and a head injury after a dramatic fall on the campaign trail, officials said.

Khan is one of two frontrunners for Pakistani prime minister. He was injured Tuesday, just four days before the country's historic election -- Pakistan's first democratic transition of power.

Khan and at least two guards were riding on a forklift up to a stage in Lahore, where Khan was to hold a rally. The men apparently lost their balance near the side of the stage and fell about 20 feet, clinging on to one another.

Khan struck his head on a metal bar jutting out of machinery on the way down. His guards were not seriously injured.

Dr. Faisal Sultan of Shaukat Khanum Hospital said Khan suffered two fractures to his spine and needs to rest, but there's no sign of any neurological damage.

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From his hospital bed, Khan urged citizens to vote in Saturday's election. His injuries cut short a grueling schedule of 50 rallies across Pakistan in eight days.

His main opponent, Nawaz Sharif, decided to postpone campaigning out of respect for Khan.

Pakistan's democratic elections to select a new government have been plagued by deadly violence in recent weeks, and the Pakistani Taliban has claimed responsibility for several hits on candidates' campaigns.

At least 16 people died Tuesday in two attacks in Khyber Pakhtunkhwa province; one attack targeted a Pakistan People's Party rally, and the other targeted a candidate for the Jamiat Ulema-e-Islam-Fazal Ur Rehman group, police said.

And on Monday, an explosion killed 18 people at a rally for Jamiat Ulema-e-Islam-Fazal Ur Rehman, a right-wing religious party with sympathies for the militant Taliban movement.

Incidentally, the Pakistani Taliban claimed responsibility for that blast. It said it attacked because one of the candidates, Munir Orakzai, has handed over members of the mujahedeen to the United States.

"We will never forgive him nor leave him alive," a statement from Pakistani Taliban spokesman Ihsan Ullah Ihsan said.

The anti-Taliban Awami National Party and the Muttahida Quami Movement and their personnel also have been targeted recently.

On Saturday, three people were killed in back-to-back explosions near the MQM headquarters in Karachi, police said.

The MQM, one of Pakistan's largest and most liberal parties, is firmly opposed to the Islamist militant group.

Ihsan, the Pakistani Taliban spokesman, called CNN and said his group claimed responsibility for the Karachi explosions.