According to the health ministry, at least another 25 people were wounded in the clashes that erupted when fans tried to force their way into the venue to watch a game.
The violence prompted the government to postpone the Egyptian Premier League indefinitely, the prime minister’s office said in a statement.
The match between Zamalek and Enbi was open to the public, unlike most other games between Egyptian football clubs since deadly stadium riots in Port Said in 2012.
“We were inside the stadium when the clashes began outside. There was a police car on fire and they were shooting birdshot and tear gas,” a witness told AFP.
“The people fled into the desert to escape” the clashes in the northeastern Cairo stadium, he said.
The interior ministry had restricted to 10,000 the number of spectators allowed into the stadium, and tickets quickly ran out.
Thousands of fans without tickets scaled the stadium walls before police dispersed them, the ministry said.
Zamalek supporters aimed fireworks at the police who fired tear gas and birdshot, police and witnesses said.
A health ministry official told AFP some of the dead had suffered broken necks.
An AFP correspondent outside the morgue saw coroner reports handed out saying two of those killed died of “extreme pressure to the chest.”
Many of those injured suffered broken bones and bruising, the health ministry said according to state news agency MENA.
The match continued despite the violence, provoking further outrage among the fans.
Zamalek defence player Omar Gaber was later suspended for refusing to play in the match in protest at the violence, a statement from his club said.
The government accused the football fans of starting the clashes with police, leading to the deaths.
“Because of these sad events it has been decided to postpone the league to a time that will be decided later,” it said in a statement.
-‘Police are killing them’-
Outside a Cairo morgue where the bodies were taken, dozens of relatives wept and wailed while others pored over a list of the dead trying to identify loved-ones.
“The youths are supposed to be building this country and the police are killing them,” one man shouted.
Others scuffled with morgue security men who were blocking their access.
Morgue officials later placed a computer outside showing pictures of the dead men for relatives to identify.
The state prosecutor ordered an investigation into the clashes, a statement from his office said.
The statement said the fans had blocked a road leading to the stadium and torched three police vehicles.
Sunday’s deaths could inflame football fans who have repeatedly clashed with police over the past few years and can mobilise thousands of youths.
In February 2012, more than 70 people were killed and hundreds injured in post-match violence following a game in Port Said between Cairo’s Al-Ahly and Al-Masry.
The riots were the deadliest in Egypt’s sports history.
A court handed out death sentences to 21 people over that violence before an appeals court ordered a retrial that is yet to conclude.
The 2012 riots took place under a military regime that had taken charge after a popular uprising, in which football fans played a key role, ousted veteran strongman Hosni Mubarak.
The fans have continued to be a volatile force in the troubled country.
Following the Port Said stadium riots in 2012, hundreds of Cairo Al-Ahly football fans confronted police in deadly clashes in the capital- AFP