Ten people had to be taken to hospital after being overcome by carbon monoxide fumes from a barbecue thought to have been used to warm a house.
All 13 people escaped from the property in Plantation Road in Sawston, Cambridgeshire, at about 01:30 BST, after a carbon monoxide alarm went off.
However, 10 had to be taken to hospital in ambulances.
A fire service spokesman said using a barbecue indoors was “extremely dangerous” and also a fire hazard.
Wayne Swales, from Cambridgeshire Fire and Rescue Service, said barbecues, designed for outdoor use only, should never be brought inside a property.
“Not only does it put the residents at risk of carbon monoxide poisoning, but it is also a serious fire hazard,” he said.
“Luckily, this property was fitted with a carbon monoxide alarm, which alerted the residents to the situation so they were able to seek help.
“Carbon monoxide is a silent killer and we would urge residents to think about fitting a carbon monoxide detector in their properties.”
The East of England Ambulance Service sent four ambulances and a hazardous area response team to the scene.
A spokesman said none of the 10 taken to hospital “were believed to be critically ill”.