Brazil's right-wing presidential frontrunner Jair Bolsonaro has undergone emergency surgery after he was stabbed in the stomach during a campaign event.
Mr Bolsonaro's son Flavio said his father had suffered severe blood loss and arrived at the hospital "almost dead" after the attack in the southeastern city of Juiz de Fora on Thursday.
The surgeon who operated on Mr Bolsonaro said the 63-year-old had suffered multiple internal injuries to the small and large intenstine during the attack.
"It was necessary for us to not just treat one point (of entry) but a number of them inside the small intestine," Dr Luiz Henrique said at a news conference.
Mr Bolsonaro is in a serious but stable condition and will remain in intensive care for at least seven days, the doctor said.
Images on Brazilian television and social media showed Mr Bolsonaro being carried on the shoulders of a throng of supporters, before a man lunges at his stomach.
Presidential candidate Jair Bolsonaro on the shoulders of a supporter moments before being stabbed during a campaign rally in Juiz de Fora, Brazil | Image: Antonio Scorza/AP/Press Association Images
Police confirmed to the Reuters news agency that a suspect was in custody, but did not identify him.
President Michel Temer quickly condemned the attack and instructed his minister of security to reinforce security for election candidates.
"It is intolerable to see that in a democratic state it is not possible to have a normal campaign," he said.
The attack is a dramatic twist in what is already Brazil's most unpredictable presidential election since the country's return to democracy three decades ago.
Latest polls put Mr Bolsonaro in a clear lead with 22% compared with 12% each for environmentalist Marina Silva and center-left runner Ciro Gomes.
Mr Bolsonaro, a retired army captain, is a controversial figure who has enraged many Brazilians with extreme comments, but has a devout following among conservative voters.
One of his campaign pledges has been to legalise the carrying of weapons in order to combat rising violent crime.
Police officers stand in front the Santa Casa hospital where the National Social Liberal Party presidential candidate Jair Bolsonaro is hospitalised in Juiz de Fora, Brazil | Image: Leo Correa/AP/Press Association Images
Despite being a long-serving member of Congress, Mr Bolsonaro has successfully presented himself as an outsider, untouched by the corruption scandals engulfing so much of the political elite.
Yet he has also courted deep controversy with comments attacking women and sexual minorities, as well as for praising the country's 1964-1985 military dictatorship.
Mr Bolsonaro has a huge social media following of 8.5 million people.
The only Brazilian politician currently more popular is the leftist ex-president Luiz Inacio Lula da Silva, who is in prison for corruption and has been banned from competing in October's election.
