Egyptian police have arrested 47 people after violence at a football match in the city of Port Said left at least 74 people dead.
There are reports that hundreds of people have been injured.
The game was between Al-Ahly, one of Egypt's most successful clubs, and al-Masry, a team based in Port Said.
A security official said that the violence erupted as soon as the referee blew the final whistle.
Fans of Al-Masry, which beat Al-Ahly 3-1, invaded the pitch and began to throw rocks, bottles and fireworks at the opposing fans.
The clashes in the northern city, which have been blamed by the Muslim Brotherhood on supporters of former president Hosni Mubarak, come as the country struggles with a wave of incidents linked to poor security.
Medics have said that some of the deaths were the result of stab wounds and that the death toll could rise even further.
The head of Egypt's ruling military council has said that they will form a fact finding committee to investigate the rioting.
Two military helicopters were deployed to rescue the visiting team and some of its fans from the city.
State television quoted deputy health minister Hesham Sheiha as saying that most of the injuries were caused by concussion and deep cuts.
"This is unfortunate and deeply saddening. It is the biggest disaster in Egypt's soccer history," Hesham Sheiha told state television.
Al-Ahly player Mohamed Abo Treika said Al-Masry fans invaded the pitch after the game ended.
"This is not football. This is a war and people are dying in front of us. There is no movement and no security and no ambulances," Abo Treika said.
"I call for the premier league to be cancelled. This is horrible situation and today can never be forgotten."
Gunfire was later reported on the main road leading to Port Said from Cairo.
In the capital itself, a match at Cairo Stadium was halted by the referee after receiving news of the violence in Port Said, prompting fans in Cairo to set parts of the stadium on fire.
There were no reports of injuries from that incident.