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.