Update 3:04 p.m. ET: Egyptian Vice President Omar Suleiman has urged all demonstrators to go home and observe the curfew, saying his dialogue with political forces depends on an end to street protests.
Update 11:33 a.m. ET: "The decision to crack down on the demonstrations has now been taken," says Hisham Melhem, Washington bureau chief for the Egyptian network Al Arabiya, who predicts in an interview on MSNBC TV that violence will continue through a massive anti-Mubarak protest expected after prayers Friday.
Pro-Mubarak demonstrators on camels and truck are charging into the crowd using whips and throwing molotov cocktails, witnesses report. The military is sticking to its promise not to interven with force, which has the effect today of letting pro-government crowds reign free.
All indications are that several thousand supporters of President Hosni Mubarak are instigating today's clashes.
White House chief of staff William Daley told reporters that Washington had no warning of today's events, which came as a surprise after President Barack Obama's "cordial" phone call with Mubarak yesterday, NBC News' Andrea Mitchell reports.
Looking at the larger picture, Daley said that given the country's history, the next leader could likely come from the military, with which the United States has "extensive, continuing contacts."
"We would hope what came out of this crisis is a stronger democratic, secular nation," he said, but the bottom line is that the people will control the outcome.