Four dead, including gunman, in Belgium shooting
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 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."
Interior Minister Jan Jambon said on Twitter that Belgium's anti-terror crisis centre was monitoring the situation.
Images on social media showed people rushing to safety on Liege's central boulevard d'Avroy with shots and sirens ringing in the background.
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.
Belgium remains on high alert after the 2016 attacks, claimed by the Islamic State group, left 32 people dead. Brussels-based militants were also involved in the 2015 Paris attacks.