Ugly clashes at a football match in Port Said have left at least 73 people dead and more than 1,000 injured, according to Egyptian state television.
Al-Masry claimed a rare 3-1 victory at home to Al-Ahly but shocking scenes followed the final whistle, with hundreds of the winning team's fans pouring onto the field wielding sticks and stones.
A security official claimed the supporters attacked players and opposition fans, cornering the travelling Al-Ahly faithful on the field and around the stadium and throwing stones and bottles at them.
A medic at a morgue in Port Said said some of the dead were security officers, and that most of the deaths were caused by concussions, deep cuts to the heads and suffocation from the stampede.
"This is not football. This is a war and people are dying in front of us," al-Ahly player Mohamed Abo Treika said.
"I cannot believe these things happened randomly, I don't think so, it was arranged," Al-Ahly official Hanan Zeini told the BBC.
Egypt's biggest party after recent elections, the Muslim Brotherhood, blamed supporters of ousted President Hosni Mubarak for the violent scenes.
"The events in Port Said are planned and are a message from the remnants of the former regime," Muslim Brotherhood lawyer Essam al-Erian said.
The two teams have a long history of bad blood, and clashes have erupted in recent years between their fans. The players were later taken to the dressing room for protection, Al-Ahly striker Sayed Hamdi told state TV.
Soon after the violence, a match in the Cairo Stadium between the Al-Ismailiya and Zamalek was called off in mourning for the violence, but state TV showed sections of the Cairo stadium on fire. The announcer claimed angry fans of Zamalek protested the cancellation and set alight to some sections of the stadium.
FIFA president Sepp Blatter issued a statement expressing his sympathy for the families of the victims.
"I am very shocked and saddened to learn this evening that a large number of football supporters have died or been injured following a match in Port Said, Egypt,'' the statement said.
"My thoughts are with the families of those who have lost their lives this evening. This is a black day for football. Such a catastrophic situation is unimaginable and should not happen.''
The Egyptian federation issued two statements after the incident, announcing a period of mourning and a suspension of football in the country.
"The Egyptian federation has decided to stop the football leagues in all four divisions for an indefinite period after the violence that occurred in the game between Al Masry and Al-Ahly, which represented a tragic shock to the centre of sport in general and the football family in particular.
"The federation has announced that Egyptian football will be in mourning for three days for the souls of those who have fallen victim to the violence that occurred in the wake of the Al Masry-Al-Ahly match."