The Euro 2024 qualifying fixture between Belgium and Sweden was abandoned on Monday, after a gunman shot two fans dead before kick-off.
The game was being played about five kilometres from the shooting in Brussels and over 35,000 fans were in attendance.
With the suspect still at large and reportedly going after Swedes, Belgian authorities kept fans inside the stadium for almost three hours.
Evacuation started around midnight local time.
Fans chanted “All together, all together,” inside the King Baudouin Stadium after the match was halted, with thousands of supporters from both sides also shouting “Sweden, Sweden!”
Manu Leroy, the CEO of the Belgian soccer union, said: “It was decided in the first place that the match should go ahead because the stadium was the safest place to be at the time, so that the fans could stay here and be safe.”
Eric Van Duyse, spokesperson for the federal prosecutor’s office, told reporters the investigation was centering on “a possible terrorist motivation for the shooting.”