US Secretary of State Hillary Clinton urged both sides to show restraint.
Thousands defied the night curfew in the capital Cairo and were trying to storm two major government buildings — the state TV and the Foreign Ministry. Others were praying on the streets of Cairo after nightfall.
Flames rose up across a number of cities from burning tires and police cars. Even the ruling party headquarters in Cairo was ablaze in the outpouring of rage, bitterness and utter frustration against the government. Some protesters were looting television sets and electric fans from the burning headquarters.
One protester was killed, bringing the death toll in four days of protest to eight.
"I can't believe our own police, our own government would keep beating us up like this," said Cairo protester Ahmad Salah, 26.
Internet and cell phone services, at least in Cairo, appeared to be largely cut off since Thursday night in the most extreme measure so far to try to hamper protesters from organizing. However, that did not prevent tens of thousands from flooding the streets, emboldened by the recent uprising in Tunisia.
In one of many astonishing scenes Friday, thousands of anti-government protesters wielding rocks, glass and sticks chased hundreds of riot police away from the main square in downtown Cairo and several of the policemen stripped off their uniforms and badges and joined the demonstrators. An Associated Press reporter saw the protesters cheering the police who joined them and hoisting them on their shoulders.
After chasing the police, thousands of protesters were able to flood into the huge Tahrir Square downtown after being kept out most of the day by a very heavy police presence. Few police could be seen around the square after the confrontation.
The protesters were energized Friday by the return of Nobel Peace laureate Mohamed El-Baradei, one of the country's leading pro-democracy advocates. He returned to the country Thursday night after a month abroad, declaring he was prepared to lead the opposition to a regime change.
When he joined protesters Friday after noon prayers, police fired water cannons at him and his supporters. They used batons to beat some of El-Baradei's supporters, who surrounded him to protect him.
A soaking wet El-Baradei was trapped inside a mosque while hundreds of riot police laid siege to it, firing tear gas in the streets around so no one could leave. Tear gas canisters set several cars ablaze outside the mosque and several people fainted and suffered burns.
When he returned home police stationed outside told him he was not allowed to leave again.
After nightfall, thousands of protesters defied a curfew, massing outside the Egyptian television building where at least one tank was stationed, and urged the army to support their cause.
"The army and the people, together!" they chanted in front of the building that also houses the Information Ministry and is near the Foreign Ministry building.
In the canal city of Suez, protesters overran a police station, seized weapons and torched security force vehicles in fierce clashes during which a protester was killed.
In Alexandria, protesters overran police lines and torched police trucks, a witness said. In several cities, protesters stormed the offices of the ruling National Democratic Party, witnesses reported.
But in a hint that authorities might heed public anger, a senior lawmaker and member of the ruling party called for "unprecedented reforms" in order to stave off a revolution. Mustafa al-Fekki, NDP member and chairman of parliament's foreign affairs committee, said security forces alone could not prevent revolution in Egypt, that reform was necessary.
"Nowhere in the world can the security forces put an end to revolution," he said in remarks to Al Jazeera television. "The security option alone is not sufficient, and the president is the only one to put an end to these events," he added, calling for "unprecedented reform."
