JK Rowling and Stephen King are among the authors and notable faces voicing their disbelief after Salman Rushdie was stabbed on stage in New York state.
The 75-year-old Indian-born British author, whose writing led to death threats from Iran in the 1980s, was to deliver a lecture at the Chautauqua Institution when the incident occurred, leaving him with an apparent stab wound to the neck.
As he was transported to hospital by helicopter, with his condition unclear, a number of authors took to social media to speak of their shock following the "horrific" incident.
"Horrifying news," Rowling said on Twitter: "Feeling very sick right now. Let him be ok."
Renowned American author of horror and fantasy novels King said: "I hope Salman Rushdie is okay."
Journalist and author of Empireland, Sathnam Sanghera, tweeted: " ++Passage from Midnight's Children in my last ever exam. Poster of The Moor's Last Sigh had place on my (pretentious) student bedroom wall. Quote from Satanic Verses opens Empireland.
"Lots of British Asian writers wouldn't be writers without him. Pray he's well."
TV chef Nigella Lawson wrote: "This is horrific. Am distraught. Please, please let him be ok."
A number of political figures also shared their shock, as photos emerged from the Associated Press news agency showing author lying on his back with a first responder crouched over him.
Rushdie's The Satanic Verses has been banned in Iran since 1988, as many Muslims view it as blasphemous, and its publication prompted Iran's then-leader Ayatollah Khomeini to issue a fatwa calling for his execution.
Conservative leadership hopeful Rishi Sunak said on Twitter: "Shocked to hear of the attack on Salman Rushdie in New York. A champion of free speech and artistic freedom. He's in our thoughts tonight."
Transport Secretary Grant Shapps tweeted: "Shocked to hear that @SalmanRushdie has been stabbed in New York. Freedom of speech is fundamental to all strong democracies. Thoughts with him and his family."
Shadow foreign secretary, Labour's David Lammy, also wrote: "This is just horrific. Salman Rushdie is a lion of a man and a hugely talented author.
"Praying he makes a full recovery and his cowardly attacker is brought to justice," added Lammy. - dpa