Belgium's Euro 2024 qualifier against Sweden was abandoned at half-time after police confirmed two people had been shot dead in Brussels before the game on Monday night.
A gunman claiming to be a member of terrorist group Islamic State opened fire on a group of Swedish football fans, two of whom were killed. A third is said to be seriously injured.
Footage posted by Belgian newspaper Het Laaste Niews showed a man in an orange jacket on a scooter firing a rifle and taking cover in a nearby building. He has since been killed by police.
A statement from Belgium prime minister Alexander De Croo reads: "I have just offered my sincere condolences to Ulf Kristersson following tonight's harrowing attack on Swedish citizens in Brussels.
"Our thoughts are with the families and friends who lost their loved ones.
"As close partners the fight against terrorism is a joint one."
The game reached half-time at Stade Roi Baudouin after goals from Viktor Gyokeres and Romelu Lukaku but the two sides did not emerge for the second half. According to Swedish broadcaster TV6, the Sweden players told UEFA they did not want to continue playing and and Belgium team agreed.
A post from Belgian Red Devils on social media reads: "Due to the incidents in Brussels earlier tonight, play is suspended. Our thoughts are with all those affected."
UEFA later added: "Following a suspected terrorist attack in Brussels this evening, it has been decided, after consultation with the two teams and the local police authorities, that the UEFA Euro 2024 qualifying match between Belgium and Sweden is abandoned. Further communication will be made in due course."
Fans have been told to stay in the stadium by police for their safety. Belgian authorities have raised Brussels' terror alert to its highest level and its second-highest in the rest of the country.
A minute's silence was observed before the Euro 2024 qualifier and supporters were visibly distraught in the stands.
Stade Roi Baudouin is located in the north-western district of Brussels, around 6.4km from Boulevard d'Ypres where the shooting took place.