Authorities are now reporting the attack came from a single gunman armed with grenades and a rifle.
LIEGE, Belgium (AP) -- Several men armed with hand grenades and guns attacked a busy bus stop in eastern Belgium on Tuesday, killing at least two people and wounding about a dozen, officials and media reports said.
The attack left blood splattered across the cobblestones of the central area of Liege city, which was crowded with people doing Christmas shopping in nearby markets.
Footage from the scene showed people, including a large group of children, fleeing down the streets of the city center - some still carrying shopping bags. Ambulances and police vehicles descended on the area.
Officials and the media reports had no information about the identity of the two or three assailants or what could have motivated their attack. But the Belgian public broadcaster VRT reported they remained at large and police were telling residents to stay in their homes or seek shelter in shops or public buildings.
Another broadcaster, Radio Television Belge Francophone, said all buses had been asked to leave the city center and all shops in the area were closed, some with many customers stranded inside.
News reports said police helicopters are flying over the city and a medical post has been set up in the courtyard of the palace of the Prince Bishops court house located on the site.
About a dozen people were reported to have been wounded.
VRT Radio spoke with Herve Taveirne from the courthouse into which he had fled to escape the gunfire.
"We were in the courthouse building and were just leaving when we saw someone toss a grenade," Taveirne said. "I grabbed a little boy ... and took him back into the courthouse. Outside the building I heard shooting ... Our lives were in danger. This man was shooting in any direction. We ran for our lives at that point."
The television channel La Une said a man with a Kalashnikov automatic weapon had opened fire on a bus.
The situation was chaotic, and reports were conflicting as to the number of assailants. Many news organizations reported that one of the dead was an attacker.
In Brussels, Interior Ministry official Peter Mertens confirmed the attack and said at least one or two assailants were involved and at least one person was killed and several were wounded. Emergency medical teams were called in from as far away as the Netherlands, Mertens said.
Phone calls to Liege authorities were not immediately answered.
The daily newspapers Le Soir and La Capitale reported that three assailants lobbed grenades into a crowd at the bus shelter and opened fire with guns. Belgian media reported that one of the attackers was apparently killed, a man believed to be about 40 years old. The daily La Meuse newspaper said an attacker had killed himself.
New reports said the attack began at about 12:30 p.m. (6:30 a.m. EST) when the men lobbed several grenades at the bus shelter in Place Saint-Lambert, a busy downtown square. The reports said witnesses reported four explosions and gun fire.
An unidentified man who was wounded in the attack told Belgium's VRT television network that "someone threw grenades and fired shots."
Police were on the scene quickly and sealed off the square.
Valerie Schaaps, a spokeswoman for the prosecutors office in Brussels, confirmed there had been explosions and gunfire, causing injuries.
Place Saint-Lambert is a busy crossroads. Every day 1,800 buses serve the square, which leads to downtown shopping streets. The Place Saint-Lambert and the nearby Place du Marche host the Liege's annual Christmas market which consists of 200 retail cabins and attracts some 1.5 million visitors a year.
AP correspondents Don Melvin, Gabriele Steinhauser and Robert Wielaard in Brussels contributed to this report.