A gunman shot dead three people, two of them policemen, in the eastern Belgian city of Liege on Tuesday before being killed by elite officers, prosecutors told AFP.
The shooting occurred around 10:30 am (0830 GMT) near a high school on a major artery in the city, which lies some 90 kilometres (55 miles) east of Brussels.
But the attacker’s motive was not immediately clear, with Catherine Collignon, spokeswoman for the Liege prosecutors office, telling AFP: “We don’t know anything yet.”
Media reports said the gunman shot dead two police officers at a cafe before fleeing to the Lycee Waha school, where he took a cleaning lady hostage.
The gunman was shot dead by an elite police unit, prosecutors said.
Belgian Interior Minister Jan Jambon said Belgium’s Federal Crisis Centre was monitoring the situation.
“Our thoughts are with the victims of this horrible act. We are in the process of establishing an overview of exactly what happened,” Jambon wrote on Twitter.
The crisis centre said a security cordon had been set up around the area and urged people to stay away.
Belgium has been on high alert since the smashing of a terror cell in the town of Verviers in January 2015 that was planning an attack on police.
The Verviers cell also had links to Abdelhamid Abaaoud, the mastermind of the November 2015 Islamic State attacks on Paris that killed 130 people.
Belgium further raised its terror alert level after the Paris attack, and placed the capital Brussels on lockdown for a week.
Belgium was then hit by its own IS suicide attacks on Brussels airport and a metro station which killed 32 people.