Defendants pleaded not guilty on Tuesday in the trial of 75 people over Egypt's worst football disaster, which left more than 70 people dead in Port Said in February.
The violence was one of the deadliest incidents in football history, and came amid charges from witnesses that security forces did little to prevent the rioting, prompting more deadly clashes in the days that followed.
Nine policemen are among the defendants in the trial, which is being held in Cairo for security reasons, amid massive security.
The accused began to plead not guilty as some chanted "Allahu Akbar" (God is greatest), denying the charges of premeditated murder and possession of weapons.
Amid chaotic scenes aired live on television, defendants dressed in white climbed on benches inside a holding cage, pointing to security officials on trial in the same case and blaming them for the violence.
One of the accused shouted that he had been brought in as a witness in the case but was shocked to find out that he had been charged along with the rest.
"We will die like them, or bring them justice," the defendants cried, echoing the chant on the streets during the protests that followed the football disaster on February 1 in the northern city.
The hearing was adjourned until May 5, when the court will hear witness testimonies.
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Relatives of those who died, some holding pictures of their dead loved ones, sobbed in court, while hundreds of football fans gathered outside the court demanding justice for the dead.
The clashes in the Suez Canal city between fans of home side Al-Masry and Cairo's Al-Ahly erupted at the final whistle.
Al-Masry fans invaded the pitch after their team beat the visitors 3-1, throwing rocks, bottles and fireworks at Al-Ahly supporters, causing chaos and panic as players and fans fled in all directions.
The Port Said stadium deaths also sparked days of violent protests in Cairo, in which another 16 people were killed.
The prosecutor said the accused, many of whom are Al-Masry supporters, started the violence that killed the Al-Ahly fans "in revenge for prior differences between them, and in a show of force."
Many Egyptians believe the football riot was orchestrated either by the police or by supporters of ousted president Hosni Mubarak, a reflection of the distrust felt towards the country's ruling military.
The most ardent supporters of Al-Ahly and another Cairo side, Zamalek, known as Ultras, were active in the revolt that overthrew Mubarak.
They played a prominent role in defending anti-regime protesters when, one day during the uprising, Mubarak supporters on horse and camel back plunged into the crowds in Cairo's Tahrir Square before being pulled from their mounts or fleeing.