Author Salman Rushdie, 75, appears to have been stabbed in the neck on stage at an event in New York state, according to police.
A man stormed the stage as the famed novelist was about to give a lecture at the Chautauqua Institution, an arts and education centre.
Rushdie was treated on stage then taken to hospital by helicopter.
A suspect was arrested at the scene and is in custody, New York State Police say.
Rushdie faced death threats and went into hiding for nearly a decade after his book The Satanic Verses was published in 1988.
Iran at the time issued an edict calling for his death.
Rushdie, the author of 14 novels, was knighted in 2007 for services to literature.
Salman Rushdie’s publishers, Penguin Random House have joined the condemnation of the attack, describing it as a “violent public assault”.
“We are deeply shocked and appalled to hear of the attack on Salman Rushdie while he was speaking at the Chautauqua Institution in New York. We condemn this violent public assault, and our thoughts are with Salman and his family at this distressing time”, Markus Dohle said.
We’re getting a little more from Salman Rushdie’s literary agent, who just confirmed he was in surgery.
Andrew Wylie tells the BBC’s US partner station CBS that he doesn’t have an update on Rushdie’s condition – but says he will pass on any news when he gets it.
The Muslim Council of Britain is the latest organisation to condemn the attack in the US on author Salman Rushdie.
“Such violence is wrong and the perpetrator must be brought to justice,” it says in a tweet.
UK Prime Minister Boris Johnson joins other British politicians condemning the attack, saying he’s appalled that Salman Rushdie was stabbed “while exercising a right we should never cease to defend”.
“Right now my thoughts are with his loved ones. We are all hoping he is okay,” he says in a tweet.