Leading Pakistani politician Imran Khan has been hurt after falling off a makeshift lift that was taking him onto a stage at an election rally in Lahore.
He suffered a visible head injury, but a spokesman for the Shaukat Khanum hospital said his condition was stable.
The former cricketer later appeared on television from his hospital bed.
He urged Pakistanis to vote in Saturday’s parliamentary elections, in which his Pakistan Tehreek-e-Insaf (PTI) party is expected to do well.
Former Prime Minister Nawaz Sharif – who leads the rival Pakistan Muslim League-N and is slightly ahead of Mr Khan in the polls – announced he was suspending his campaign for a day, out of respect for his opponent.
Dramatic television pictures from Tuesday’s campaign rally showed Mr Khan falling about 5m (15ft) from the lift platform together with several others, some of whom appeared to land on top of him.
“Whether Nawaz Sharif’s response was shrewd or sympathetic, will the man who’s been regarded as the front runner escape any political injury?”
A dazed and bloodied Mr Khan was later seen being carried away by supporters to a vehicle which drove him to a local hospital.
After receiving initial treatment he was moved to Lahore’s Shaukat Khanum Memorial Cancer Hospital, which he founded.
Dr Faisal Sultan, the hospital’s chief executive, told reporters that Mr Khan had stitches to his head and had suffered a hairline compression fracture on a vertebra on his back.
“Imran has a head injury, but he is stable, talking and recognising people. We will conduct some tests and further examinations.”
He will be kept under observation and specialists will examine him again on Wednesday. The chairman of PTI, Asad Omar, told Geo News that doctors had asked Mr Khan to rest 15 days, but that he wished to resume political activities.
Imran Khan speaking on Dunya TV from hospital (7 May 2013) Speaking from his hospital bed, Mr Khan told voters to decide whether they wanted a new Pakistan
Outside the hospital, hundreds gathered awaiting word of his condition. Many chanted “Long live Imran Khan”.
Three hours after the accident, the PTI leader spoke to a local television station from his hospital bed, wearing a blue gown and looking drained.
“I have done whatever I could do,” he told Dunya TV. “Now you have to decide whether you want to make a new Pakistan.”
“You have to come out for your rights on 11 May.”
The PTI leader has been campaigning relentlessly in the run-up to Saturday’s poll and briefly collapsed on stage earlier this week, says the BBC’s Orla Guerin in Islamabad.
Mr Khan is one of the key candidates in the election, and the PTI has been gaining momentum, our correspondent adds. He believes a “tsunami” of support will sweep him to power.