Agent says 'the news is not good' as author, subject to Iranian death fatwa, remains in hospital; police arrest Hadi Matar, who reportedly has sympathies for Shia extremists

Knife attack comes 33 years after Iran's supreme leader called on followers to rapidly execute author who was accused of insulting Islam and the Prophet Muhammad

Condition of author, who was speaking at event in New York State, not immediately clear; his novel 'Satanic Verses' prompted calls for his death and a bounty of over $3 million