The cause of the blast, which almost destroyed a house, is under investigation.
Footage showed scores of people fleeing the scene after the blast which happened around 4 pm on Sunday.
The house ,where the blast took place, has been almost destroyed with its front and rear portions blown away by its impact.
Passers-by helped residents escape from the building. As many as 13 people are undergoing treatment in various hospitals in Verviers and Eupen.
Witnesses posted numerous photos on Twitter, which showed three floors of the building damaged. Some users suggested a gas explosion.
Firefighters were working at the scene.
“The neighboring houses were also affected. Firefighters must first secure the area and then search the rubble,” Muriel Targnion, the town’s mayor, said.
Residents of nearby building have been evacuated, RTL added.