Liege, Belgium: A man killed two policewomen and a woman passerby in the Belgian city of Liege on Tuesday, public broadcaster RTBF said, before being shot dead in an exchange of fire that sent people scattering and scurrying to take cover.

The city authorities confirmed the death toll.

The national crisis centre, on high alert since past attacks by Islamic State in Paris and Brussels, said it was looking into whether terrorism might have been a motive for Tuesday's attack in Belgium's third-largest city.

RTBF named the alleged assailant as a 36-year-old Belgian who had been released on parole from a prison near Liege, close to the German and Dutch borders, on Monday.

He was serving time for drug offences and classified as "unstable", according to RTBF. It remained unclear how the incident, during which pupils at a nearby high school were moved to a place of safety, had unfolded.