Belgian police are searching Tuesday for a Tunisian man who killed two Swedish football fans as they investigate a possible terrorist-related motive.

One victim was Swedish and the other was of Swedish origin, and federal prosecutors said that may have been a motivation in the shooting.

European cities have been on high alert for possible extremist acts after the attacks by Hamas in Israel. But prosecutors said late Monday that there was no indication yet of a link to the conflict.

The 45-year-old suspect was staying illegally in Belgium, Prime Minister Alexander De Croo said in a news conference Tuesday morning.

A video circulated on social media site with a man declaring in Arabic that he shot several Swedes out of revenge and was inspired by the Islamic State terrorist group. The authenticity of the video couldn’t be determined immediately. The suspect remains at large.

Read more: Sweden Sees First Hate Speech Conviction After Koran Burning

“Horrified by the terrorist attack which left two victims in the heart of Brussels,” Belgian Foreign Minister Hadja Lahbib said in a post on the X social media network. “All necessary means must be mobilized to combat radicalism.”

Sweden and Belgium were playing a European Championship qualifier football match in Brussels, but the game was suspended at halftime after the news of the shooting. Fans were asked to remain in the stadium for safety, and were eventually evacuated.

Brussels raised its threat level to 4, which asks people to avoid non-essential movement. Many schools were closed on Tuesday, but flights are continuing in and out of Brussels, and public transit is operating normally.

“Terrorism will never win,” De Croo told reporters.

--With assistance from Jorge Valero and Maria Tadeo.