The tweets were posted between 2 a.m. and 3 a.m. Eastern Time by the "foxnewspolitics" account. The account has a badge with a checkmark that means it has been verified by Twitter for authenticity.

National media outlets in the U.S., including Fox News itself, carried no such reports. Fox News ran a story on its website , saying it "regrets any distress the false tweets may have created." The false tweets came on a major U.S. holiday, Independence Day.

The first tweet about the assassination -- addressed directly to Obama's real account -- said has just passed. The President is dead. A sad 4th of July, indeed. President Barack Obama is dead."

Subsequent tweets said that Obama had been shot twice in the lower pelvic area and the neck and that he later died from his wounds, with the shooter unknown.

Earlier on Monday morning, the Huffington Post reported that the Fox News Politics Twitter feed had been hacked. A showed the Fox News Politics feed carrying the subtitle: "H4CK3D BY TH3 5CR1PT K1DD3S." The channel's logo had been replaced with the capital letters SK, presumably also a reference to script kiddies, a term applied to youths who hack computers using simple, automated tools or scripts developed by others.