Four people suffered carbon monoxide (CO) poisoning in a house in Braine-l'Alleud on Saturday morning, according to local police.
Firefighters from the Walloon Brabant rescue zone arrived at the property on Chaussée d'Alsemberg at around 10:00.
Two residents of the house, aged 70 and 80, and two neighbours, aged 23 and 51, who came to assist them, suffered CO poisoning.
All four victims were taken to the hospital for oxygen treatment and were discharged later that day.
The poisoning was caused by a fault in the house's boiler.
"The concentrations which were recorded were significant," said a police spokesperson, noting that the neighbours' intervention was life-saving.
