ElBaradei, Nobel peace laureate and former IAEA chief, was confined to his residence as unprecedented countrywide protests turned violent forcing police to fire rubber bullets, tear gas and use water cannons.
Egyptian state TV said 82-year-old Mubarak has ordered night curfew from 6 pm to 7 am in Cairo, Alexandria and Suez cities and that military will work along with the police to impose the restrictions.
On his part, Mubarak, who was reported to be in poor health, was conspicuous by his absence from the public eye as cries of change grew louder in the largest Arab state on the fourth-day of protests that has left seven people dead.
The escalation of protests for Mubarak's ouster came against the backdrop of widespread resentment over rising unemployment, food prices and corruption.
In an unprecedented crackdown, authorities cut Internet and cell-phone data services across the country in a bid to hamper protesters from organising mass rallies after Friday noon prayers as part of the biggest challenge to Mubarak who has ruled for nearly three decades.
Raising slogans against Mubarak, protesters shouted "out...out" as they marched with bodies of victims in Suez, where they ransacked the headquarters of ruling National Democratic Party.
In Cairo, protesters marched towards major squares setting off clashes with the police. Police armed with batons beat some of ElBaradei's supporters, who surrounded him to protect him, and fired rubber bullets into the crowd and used tear gas and water cannons to disperse the protesters outside a mosque in Giza square in the Egyptian capital. Several journalists were also reported to have been roughed up.
Arabic TV channel Al Arabia reported that police penned 68-year-old ElBaradei, who returned to his homeland last night to lead the protests, in the protest area. A soaking wet ElBaradei was reported to have been trapped inside a mosque for nearly one hour.
Arabic channel Al Jazeera initially reported that ElBaradei was detained but later clarified that he was only not allowed to leave an area by the police.
Hundreds of riot police laid siege to the mosque, firing tear gas in the streets surrounding it so no one could leave. The tear gas canisters set several cars ablaze outside the mosque amid reports that several people fainted and suffered burns.
As the Egyptian capital descended into violent chaos, large groups of protesters gathered at at least six venues in the Egyptian capital which is home to about 18 million people.
ElBaradei, one of Mubarak’s fiercest critics, claimed that Mubarak's regime was on its "last legs".
Television stations also reported clashes between protesters and police in several other major Egyptian cities, including the Mediterranean port city of Alexandria, Minya and Assiut south of Cairo, al-Arish in the Sinai peninsula and in the Delta city of Mansura.
In Alexandria, protesters threw stones at police who retaliated with tear gas, water cannon and rubber bullets after prayers ended with cries of "God is great" followed by "We don't want him," referring to Mubarak.
At Ramsis square in the heart of the city, thousands of protesters clashed with police as they left the al-Nur mosque after the prayers.
At the upscale Mohandiseen district, at least 10,000 of people were marching toward the city center chanting "down, down with Mubarak."
In the north Sinai town of Al-Mahdia, near the Israeli border, hundreds demanded the release of political prisoners and an end to police heavy-handedness, al Arabia reported.
The demonstrations are backed by both the country's biggest opposition group--the Muslim Brotherhood-- and ElBaradei, galvanising the protests.
"It is a critical time in the life of Egypt. I have come to participate with the Egyptian people," ElBaradei said before leaving Cairo airport after his arrival from Vienna.
"We're still reaching out to the regime to work with them for the process of change. Every Egyptian doesn't want to see the country going into violence," he said, adding "Our hand is outstretched."
"I wish that we didn't have to go to the streets to impress on the regime that they need to change," ElBaradei said.
At least 20 members of Egypt's opposition group, the Muslim Brotherhood, have been arrested as tensions rise ahead of the Muslim Friday prayers, the group's lawyer says.
The government deployed an elite special operations force in Cairo on Thursday night as violence escalated outside the capital, and the Islamist Muslim Brotherhood called on its members to take to the streets after Friday afternoon prayers.
Thousands of black-clad riot police armed with batons and shields were deployed across the city, with the largest concentrations at Tahrir, or Liberation, Square at the heart of the city, where 10,000 protesters gathered for their first demonstration on Tuesday.
The police, backed by armoured vehicles and fire engines fitted with water cannon, were also deployed in large numbers at Ramsis Square, another flashpoint in central Cairo.
The interior ministry has already warned of "decisive measures" against the protesters demanding Mubarak's ouster.
The protests are inspired by the revolt that brought down Tunisia's president recently.