The scuffles erupted when fans of Al-Masry stormed the field following a rare 3-1 win against Al-Ahly. Al-Masry supporters hurled sticks and stones as they chased players and fans from the rival team, who ran toward the exits and up the stands to escape, according to witnesses. One man told state TV he heard gunshots in the stadium, while a lawmaker from Egypt's powerful Muslim Brotherhood said the police didn't prevent fans carrying knives from entering the stadium.
TV footage showed Al-Ahly players rushing for their locker room as fistfights broke out among the hundreds of fans swarming on to the field. Some men had to rescue a manager from the losing team as he was being beaten. Black-clothed police officers stood by, appearing overwhelmed.
The Interior Ministry said 74 people died, including one police officer, and 248 were injured, 14 of them police. A local health official initially said 1,000 people were injured and it was not clear how severely. Security forces arrested 47 people for involvement in the violence, the statement said.
State TV appealed to Egyptians to donate blood for the injured in Port Said, and the military sent two aircraft to evacuate serious cases to the capital, Cairo.
Field Marshal Hussein Tantawi, the head of the military leadership that assumed power after Mubarak's ouster, welcomed Al-Ahly team players who were flown back to Cairo from Port Said on a military aircraft.
"This will not bring Egypt down," he told reporters at a military air base east of Cairo. "These incidents happen anywhere in the world. We will not let those behind it go ...This will not affect Egypt and its security."
The military declared three days of mourning starting Thursday.
Interior Minister Mohammed Ibrahim told state TV that 13,000 Al-Masry fans stormed the field, jumping a low fence and attacking about 1,200 Al-Ahly fans. He transferred the Port Said local security chief to a desk job as a punitive measure.
Al-Ahly goalkeeper Sharif Ikrami, who was injured in the melee, told the private station ONTV that dead and wounded were being carried into the locker room.
"There were people dying in front of us," he said. "It's over. We've all made a decision that we won't play soccer any more. How will we play soccer after 70 people died? We can't think about it."
Hesham Sheiha, a health ministry official, said most of the deaths were caused by concussions, deep head wounds and suffocation from the stampede. He said 40 people were seriously injured.
In an interview with the team's station, Mohammed Abu Trika, a player with Al-Ahly, criticized police for standing by and not intervening in the violence.
"People here are dying and no one is doing a thing. It's like a war," he told the team TV station. "Is life this cheap?"
Egypt's state prosecutor ordered an immediate investigation into the violence, and the Egypt Football Association ordered an indefinite suspension of the league games. The parliament said it would convene an emergency session.
The two sides also traded conspiracy theories, with each side blaming the other for trying to destabilize the country.
Essam el-Erian, a Brotherhood lawmaker, said the military and police were complicit in the violence, accusing them of trying to show that emergency regulations giving security forces wide-ranging powers must be maintained.
"This tragedy is a result of intentional reluctance by the military and the police," he said.
The manager of the Al-Masry, Kamal Abu Ali, announced he also was resigning in protest.
"This is not about soccer. This is bigger than that. This is a plot to topple the state," he told the same station, using an often-cited allegation by the military against protesters.
Bob Bradley, the former U.S. national team coach who was hired in September as coach of Egypt's national team, was not at the stadium, U.S. Soccer Federation spokesman Michael Kammarman said.