He said he had seen what appeared to be the body of an attacker before police cleared everyone from the area. Police told him the man had shot himself, Hauzeur said.
A CNN correspondent at the scene Tuesday evening said dozens of police in fluorescent jackets remained in the cordoned-off square but it was otherwise deserted.
Oliver Moch, a spokesman for the Citadelle hospital, the largest in the Liege area, said 31 people injured in the attack had been admitted for treatment there.
The Belgian Red Cross also had a team on site in Liege, operations director Gregory Jones told CNN earlier. It was providing psychological support.
King Albert II and Queen Paola went to Liege to meet the mayor, provincial governor and workers with the Red Cross and emergency services following the attack, the Belgian royal palace told CNN.
Prime Minister Elio Di Rupo also traveled to Liege, his spokesman said.
British Foreign Secretary William Hague issued a statement saying: "There can be absolutely no place for appalling acts of violence such as this in any society, and I condemn this attack in the strongest terms."
Charles Boisoin, whose apartment overlooks the city center, told CNN shortly after the attack that he and his neighbors had been instructed by police not to leave their homes. The city center was virtually deserted and all he could hear and see were helicopters flying overhead, he said.
Television footage and images from the scene showed blood on the sidewalk, as well as police officers and vehicles gathered nearby.
The provincial governor's office initially said that police were searching for at least one suspect.
Liege is Belgium's third-largest city, after Brussels and Antwerp, the national tourist office says. Dating back centuries, it is an important cultural and industrial center for the country.
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