A gunman shot dead three people at a busy central square during a Christmas market in the Belgian city of Liege Tuesday and then killed himself, a justice official said.

More than 75 people were injured in the attack, some of them seriously, Liege's prosecutor told a news conference. As well as firing from a rifle, the gunman also threw explosives, officials and witnesses said.

Gaspard Grosjean, a journalist for a local Liege newspaper, was in the square moments after the attack.

We saw people with bullet wounds in their shoulders, their hands, he said, adding that he had seen one dead body. I see people completely scared, people are crying, everyone is on their phones.

The gunman, named as Nordine Amrani, 33, began his attack near a bus stop at Place Saint Lambert, a central shopping area and the site of the city's annual Christmas market and its main courthouse.

He ended by shooting himself in the head with a handgun, witnesses said.

It was clear not what his motive was, but justice officials said he had been summoned in the morning to appear before police and had previous convictions for illegal possession of arms and of drugs.

He has no history of terrorist acts, prosecutor Daniele Reynders told a news conference in Liege.

A spokesman for Belgium's crisis response centre also said there was no indication that it was a terrorist attack.

Belgian Prime Minister Elio Di Rupo expressed horror at the attack and travelled to the city, 90 km (56 miles) east of Brussels. Belgium's king and queen also planned to visit.

The police closed down the centre of Liege for a number of hours, with helicopters circling overhead and ambulances arrived from as far away as neighbouring the Netherlands.

A museum on the square said it had taken in injured people.

I can say there were injured, but don't ask me if it's five, seven, eight or nine. I don't know, said Jean-Jacques Messiaen, director of the Archeoforum museum.

Police and other officials had no immediate information on a possible motive for the attack.

(Reporting By Robert-Jan Bartunek, Ben Deighton, Philip Blenkinsop; editing by Rex Merrifield and Matthew Jones)