Saint-Jean-Baptiste de La Salle school in Saint-Gilles was evacuated late on Tuesday morning after a carbon monoxide leak, with one adult taken away and three children suffering poisoning.
According to Saint-Gilles mayor Jean Spinette (PS), a boiler malfunction caused the incident. He said a technical duct connects the boiler room to 11 classrooms.
The Brussels fire brigade confirmed the incident at the school on Rue Moris.
In an initial assessment, Spinette said one adult had been taken away, and three children had been affected by carbon monoxide poisoning.
The municipality set up a reception point at the town hall for evacuated pupils. However, only a small number were expected there, as many parents were collecting their children and older pupils had been allowed to go home.
Shortly after midday, firefighters began leaving the site, while medical teams remained in place, the mayor said.
The Rue Moris site houses both primary and secondary schools.
