The US ambassador to the United Nations says the attack on the US Consulate in Benghazi, Libya, was spontaneous.
Susan Rice says the current US assessment shows it was not a coordinated, premeditated attack.
But Rep. Mike Rogers, the House Intelligence Committee chairman, says it's too early to tell. He says classified intelligence gives pause to those who suggest attacks throughout the Middle East were coincidental.
Rice tells "Fox News Sunday" that protesters gathering near the consulate were joined by others with extremist ties. She says they brought heavy weapons possibly left over from the Libyan revolution last year.
The FBI has an ongoing investigation into the attack spurred by an anti-Muslim video produced in the US that killed Ambassador Chris Stevens and three other Americans.