Salman Rushdie, the Indian-born novelist who spent years in hiding after Iran urged Muslims to kill him because of his writing, has been stabbed in the neck and abdomen onstage at a lecture in New York state and airlifted to hospital.
He was alive and still in surgery early on Friday evening (local time), local police said.
A man rushed the stage at the Chautauqua Institution and attacked Rushdie, 75, as he was being introduced to give a talk on artistic freedom to an audience of hundreds, eyewitnesses said.
The suspect was quickly apprehended and later identified as Hadi Matar, a 24-year-old man from New Jersey, who bought a pass to the event.
"A man jumped up on the stage ... and started what looked like beating him on the chest, repeated fist strokes into his chest and neck," Bradley Fisher, who was in the audience, told Reuters.
"People were screaming and crying out and gasping."
"Just witnessed the assassination attempt on Salman Rushdie's life. Still in shock. Unsure of his condition. We are being evacuated," tweeted author Carl LeVan.
A doctor in the audience helped tend to Mr Rushdie while emergency services arrived, police said.
Henry Reese, the event's moderator, suffered a minor head injury during the incident.
Mr Rushdie, who was born into a Muslim Kashmiri family in Bombay, now known as Mumbai, before moving to the United Kingdom, has faced death threats for his fourth novel, The Satanic Verses, which some Muslims said contained blasphemous passages.
The novel was banned in many countries with large Muslim populations upon its 1988 publication.
Author has $4.6 million bounty lingering over him
A few months later, Ayatollah Ruhollah Khomeini, then Iran's supreme leader, pronounced a fatwa, or religious edict, calling upon Muslims to kill the novelist and anyone involved in the book's publication for blasphemy.
The 75-year-old author, who has previously called his novel "pretty mild", went into hiding for many years. Hitoshi Igarashi, the Japanese translator of the novel, was murdered in 1991.
The Iranian government said in 1998 it would no longer back the fatwa, and Rushdie has lived relatively openly in recent years, although Khomeini's successor as supreme leader, Ayatollah Ali Khamenei, said as recently as 2019 the fatwa remained "irrevocable".
Iranian organisations, some affiliated with the government, have raised a bounty worth millions of dollars for Rushdie's murder.
Iran's semi-official Fars News Agency and other news outlets donated money in 2016 to increase the bounty by $US600,000 ($A845,000). The bounty on the author was said to be US $3million (A$4.6m).
Fars called Rushdie an apostate who "insulted the prophet" in its report on Friday's attack.
Rushdie published a memoir in 2012 about his life under the fatwa called Joseph Anton, the pseudonym he used while under British police protection.
His second novel, Midnight's Children, won the 1981 Booker Prize.
Leaders, authors denounce brutal attack: 'Feeling very sick'
British Prime Minister Boris Johnson said he was appalled Rushdie was "stabbed while exercising a right we should never cease to defend".
Former British PM Gordon Brown also condemned the "shameful" incident while French president Emmanuel Macron labelled it "a cowardly attack by the forces of hatred and barbarism".
Harry Potter author J.K. Rowling and famed horror writer Stephen King were among the many authors to express shock and dismay at the news.
"Feeling very sick right now. Let him be ok," Ms Rowling tweeted.
Rushdie giving talk about asylum for authors
Mr Rushdie was at the institution in western New York for a discussion about the United States giving asylum to writers and artists in exile and "as a home for freedom of creative expression", according to the institution's website.
There were no obvious security checks at the event, according to attendees.
"I felt like we needed to have more protection there because Salman Rushdie is not a usual writer," Anour Rahmani, an Algerian writer and human rights activist who was also in the audience, said.
"He's a writer with a fatwa against him."
Michael Hill, the institution's president, said at a news conference, "Our whole purpose is to help people bridge what has been too divisive of a world.
"The worst thing Chautauqua could do is back away from its mission in light of this tragedy, and I don't think Mr Rushdie would want that either."
Mr Rushdie became an American citizen in 2016 and lives in New York City.
He has been a fierce critic of religion across the spectrum and outspoken about oppression and violence in his native India, including under the Hindu-nationalist government of Prime Minister Narendra Modi.
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