At least 30 people have been injured in a powerful explosion at a carnival in the Paris suburb of Villepinte; several victims are reported to be in a critical condition.

“A man with a broken arm, a child with blood on his face” in the audience and “people [were] running around in all directions to find their children,” witnesses said. At least four people suffered serious injuries. Firefighters and paramedics were immediately dispatched to the scene.

The incident occurred at around 5:30pm local time when a carnival effigy made of straw and wood caught fire, a police source explained. “Pieces of wood… have injured several people including the mayor, who was hit by a projectile in his leg,” said a witness.  It is not yet known if the explosion was an accident or a criminal act.