CAIRO: A riot broke out Sunday night outside of a major football game in Egypt, with a stampede and fighting between police and fans killing at least 25 people, Egyptian authorities said.

The riot, only three years after similar violence killed 74 people, began ahead of a match between Egyptian Premier League clubs Zamalek and ENPPI at Air Defense Stadium east of Cairo.

Such incidents in the past have sparked days of violent protests pitting the country’s hard-core fans against police officers in a nation already on edge after years of revolt and turmoil.

Three security officials, speaking on condition of anonymity, said some people died during a stampede, while others died in clashes with police.

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 only let 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 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 on condition of anonymity, 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.