New York on alert over possible revenge attacks after Bin Laden hunters wipe out Al Qaeda boss who preached hate in America

Awlaki, identified by U.S. intelligence as 'chief of external operations' for al Qaeda's Yemen branch and a Web-savvy propagandist for the Islamist cause, was killed in a CIA drone attack in a remote Yemeni town, U.S. officials said.

'We know al-Awlaki had followers in the United States including New York City, and for that reason we remain alert to the possibility that someone might want to avenge his death,' Kelly said in a statement. 'He was a powerful recruiter of terrorists in the United States,' he said.

Kelly also welcomed the reported death of a second English-speaking al Qaeda operative, Samir Khan, an American of Pakistani origin who U.S. and Yemeni officials said they believed was killed in the same drone attack.

'Khan had extensive contacts in New York City and published the English language Inspire Magazine, which instructed lone wolves on how to build bombs at home, and in the most recent issue identified Grand Central Station as a target,' he said.