Policemen and soccer fans argue during a scuffle as fans attempt to enter a stadium to watch a match, on the outskirts of Cairo February 8, 2015. [Photo/Agencies]

What caused the violence wasn't immediately clear. Security officials said Zamalek fans tried to force their way into the match without tickets, sparking clashes. Fans have only recently been allowed back at matches and the Interior Ministry planned to let only 10,000 fans into the stadium, which has a capacity of about 30,000, the officials said.

Zamalek fans, known as "White Knights," posted on their group's official Facebook page that the violence began because authorities only opened one narrow, barbed-wire door to let them in. They said that sparked pushing and shoving that later saw police officers fire tear gas and birdshot.

A fan who tried to attend the game, who spoke to The Associated Press on condition of anonymity out of fear of being targeted by police, said that the stampede was caused by police who fired tear gas at the tightly packed crowd.

"Those who fell down could not get back up again," the man said.

The Zamalek fan group later posted pictures on Facebook it claimed were of dead fans, including the names of 22 people it said had been killed. The AP could not immediately verify the images.