Two Swedish nationals have been shot dead and a third person injured in Brussels, in an attack which prosecutors are treating as terrorism.
The Belgium-Sweden Euro 2024 qualifier football match being played in the city was abandoned.
Brussels is on its highest terror alert as the gunman, who appeared to have an assault rifle, remains at large.
French President Emmanuel Macron, who was on a visit to Albania, said: “Europe has been shaken.”
A spokesman for the Belgian federal prosecutor, Eric van Duyse, urged the public to “go home and stay at home as long as the threat has not been eradicated”.
He said a man claiming to be the attacker had said in a video on social media he had been inspired by the Islamic State group.
A video shows an Arabic-speaking man saying he carried out the attack in the name of God and that he killed three people.
The video and others uploaded during the attack are being verified by police, the BBC has been told.
Federal prosecutors say a terrorism inquiry has been opened over the shooting on the Boulevard d’Ypres.
A social media video shared by newspaper Het Laatste Nieuws on Monday, but not verified by BBC News, shows a man wearing a fluorescent jacket get off a scooter armed with what appears to be an assault rifle and enter a nearby glass-fronted building.
He appears to then shoot at least one person.
Police and emergency services cordoned off nearby roads following the shooting which happened at around 19:00 (17:00 GMT).
Belgian media outlets report that the two people killed were wearing football shirts belonging to the Swedish national team.
Swedish footballers told Uefa they did not want to play the second half of the match and the Belgian team agreed, according to Swedish broadcaster TV6.
Belgian Prime Minister Alexander de Croo went on social media to offer his “sincere condolences to the Swedish PM following tonight’s harrowing attack on Swedish citizens in Brussels”.
“Our thoughts are with the families and friends who lost their loved ones,” he said. “As close partners the fight against terrorism is a joint one.”
European Commission President Ursula von der Leyen said on social media her thoughts were “with the families of the two victims of the despicable attack in Brussels”.
“I extend my heartfelt support to the Belgian police, so they swiftly apprehend the suspect,” she said. “Together, we stand united against terror.”