Three days of national mourning have been declared in Egypt after at least 74 people died in clashes between rival football fans in the city of Port Said.
Hundreds more were injured as fans invaded the pitch after a match between top-tier clubs al-Masry and al-Ahly.
Emergency meetings of the cabinet and parliament have been called.
Angry crowds closed off Cairo's Tahrir Square and state TV on Thursday morning, ahead of protests to complain of police handling of the riots.
The demonstrators used metal barriers and vehicles to close the square. There will be a march on the Interior Ministry later.
"People are angry at the regime more than anything else... People are really angry, you could see the rage in their eyes," al-Ahly supporter Mohammed Abdel Hamid told the BBC.
Funerals are expected to be held after noon (10:00 GMT) prayers in Port Said.
All Egyptian premier-league matches have been postponed indefinitely.
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Jon Leyne BBC News, Cairo
Even as the violence was continuing at the Port Said football ground, Egyptians began suspecting, wondering if darker forces were at play.
The Muslim Brotherhood, now the largest party in parliament, accused remnants of the Mubarak regime of deliberately provoking the riot in an attempt to reduce the country to chaos.
Egyptian football fans can be notoriously violent. But what immediately aroused suspicions is the fact that the al-Ahly supporters, known as Ultras, have become a political force as well. They have been at the forefront of many of the big confrontations with the security forces in the last year.
What really happened at the Port Said stadium may never fully be known. It's just as likely to have been a case of incompetence, from a police force which has been seriously under strength since they were chased off the streets in the revolution a year ago.
The immediate danger for the Egyptian authorities is of new violence, as angry football supporters take to the streets once again. But this has also provoked a new political crisis, undermining trust in the ruling military council, at a time when Egypt is moving towards presidential elections and the handover to civilian rule.
Hundreds gathered at Cairo's main railway station to receive the injured and the first bodies arriving from Port Said, with some chanting slogans against military rule.
"Everyone was beating us. They were beating us from inside and outside, with fireworks, stones, metal bars, and some had knives, I swear," one fan told a private TV station.
Army units were deployed in Port Said and joined police patrols around morgues and hospitals, but most streets had no police presence.
The army has set up checkpoints at entrances to the city.
Port Said security chief Essam Samak was sacked after the riot, state media said.
Field Marshal Hussein Tantawi, the head of Egypt's ruling army council, went to an airbase near Cairo to meet al-Ahly players who were flown back from Port Said on a military aircraft.
"This will not bring Egypt down... These incidents happen anywhere in the world. We will not let those behind it go," he said, according to the Associated Press news agency.
It is the biggest disaster in the country's football history, said the Egyptian deputy health minister.
"This is unfortunate and deeply saddening," Hesham Sheiha told state television, adding that many people died in a stampede as people tried to leave the stadium.
Some of the dead were security officers, AP quoted a morgue official as saying.
BBC News - Egypt football riot: Three days' mourning for dozens killed