"The attackers pushed and shoved the CNN crew and punched them in the head, he said, but no one was seriously hurt," CNN reports.
The protests in Cairo had been peaceful since Friday, when violence between protesters and the hated police force reached a peak. After police pulled out and the Egyptian army -- which is loved and respected by the Egyptian people -- moved in, the protests have been largely peaceful even as the crowds swelled.
This afternoon, however, violence erupted again. The army is reportedly standing by, trying to calm both sides but not intervening in the violence.
Anti-government protesters are claiming that the Mubarak supporters are actually plainclothes police officers sent by Mubarak to sow chaos. Mubarak, in announcing yesterday that he will not run for re-election in September, said the country must "choose between chaos and stability."
Al-Jazeera reported earlier that anti-Mubarak protesters had taken police IDs from the Mubarak supporters.
Egyptian state TV, however, is reporting that the Interior Minister, who is in charge of police forces, denied that they are in the square.
One woman calling in from the protests reported that the pro-Mubarak forces had arrived in Tahrir Square, which has been the center of the protests over the past nine days, on government buses. Another Al-Jazeera English correspondent reported that it appears that the Mubarak supporters are trying to take the square from protesters.
Journalists other than Cooper and his crew have been targeted as well. NBC News' Richard Engel reports from the scene that journalists have been "mobbed on the streets" by Mubarak supporters who are "angry with the foreign press.
The BBC reported earlier today that three Israeli journalists were arrested and accused of being in the country illegally on tourist visas.
Late yesterday, Mubarak announced that he will not run for re-election in September, and will spend his remaining months in office ensuring a peaceful transition. Protesters, by and large, say that isn't enough and want Mubarak to step down immediately.