News reports say at least 70 people have been killed in Egypt after clashed erupted, on Friday, between security forces and supporters of ousted President Mohamed Morsi.
A night time curfew has taken effect but many protesters remain on the streets. Television video has shown a building on fire near Cairo's Ramses Square.
Fighting in the square has left dozens of people dead. Morsi's Muslim Brotherhood says a military aircraft opened fire on demonstrators.
Security forces have been cracking down on the protesters who are holding a "Day of Rage," in defiance of the interim government-imposed state of emergency. Late Friday, the Brotherhood called for a week of daily nationwide protests.
The confrontations follow Wednesday's government crackdown on two pro-Morsi camps in Cairo.
The government says 638 people were killed during the crackdown, but the Muslim Brotherhood says the death toll is in the thousands.
Earlier Friday, Egyptian state media warned people to stay off the streets in Cairo as an operation to confront what it calls "terrorist elements" unfolds.
Egyptian state television said the army and police would deal firmly with those who violated the state of emergency. The government said its forces would use live ammunition if any government facilities were attacked.
In a Skype interview from Cairo, VOA correspondent Elizabeth Arrott described how protesters in Cairo reacted as they heard shots fired.
"All of a sudden there will be a noise and the entire crowd in unison will duck down, which is an indication that there are some kinds of shots being fired. It is not clear exactly what kind. Not tear gas or we would have seen the plumes of smoke."
Television footage showed clashes in the northern city of Tanta. News reports said security forces there fired tear gas and birdshot at protesters.
At the U.N., Egyptian Ambassador Mootaz Ahmadein Khalil told reporters his government is willing to work with all factions of society.
"We will have a political inclusive, an inclusive political process that will include all members of Egyptian society no matter what they think as long as they do not resort to violence."
Meanwhile, the U.N. announced it was sending its political affairs chief Jeffrey Feltman to Egypt next week for consultations with Egyptian authorities.
French President Francois Hollande and German Chancellor Angela Merkel have called for European Union foreign ministers to meet next week to discuss Egypt's crisis. In a Friday statement, they also called for an immediate end to the unrest.
U.S. President Barack Obama has canceled next month's scheduled military exercises with Egypt. He says traditional cooperation cannot continue when civilians are being killed in the streets.