"He then took their weapons. He used the weapons on the officers, who died," Dulieu told reporters.

Dulieu said the attacker then shot and killed a 22-year-old man in a vehicle parked nearby, and took a woman hostage in a school close to where the shooting took place outside a city cafe.

"Liege police intervened. He came out firing at police, wounding a number of them, notably in the legs. He was shot dead," the spokesman said.

A spokeswoman for the city mayor's office, Laurence Comminette, told the AP that the children at the school were safe.

A senior official at the federal prosecutor's office told the Associated Press that "there are indications it could be a terror attack."

Despite this, Yves Stevens of Belgium's federal crisis center said security in Liege is now under control and that there was no reason yet to raise the national terror threat level.

"There is absolutely no confirmation yet that the incident is terror-related," Stevens told the AP.

Prime Minister Charles Michel said only that "there was a serious incident" and that he was rushing to the crisis center to get more information.

Video posted on Twitter by a person claiming to be a witness showed people running in the area. About six gunshots could be heard.

Belgian police and military have been on alert since suicide bombers killed 32 people at the Brussels airport and subway system in 2016.