A woman and a girl have died from suspected carbon monoxide poisoning on a boat on Lake Windermere in Cumbria.
North West Ambulance Service said the pair were found on a boat by the jetty near Glebe Road, Bowness, just after 16:00 BST.
They went into cardiac arrest and were taken by air ambulance to the Royal Lancaster Infirmary.
Cumbria Police later reported the woman, 36, and girl, aged 10, were dead.
The force said it was called to reports that three people on a private boat were having serious breathing difficulties.
The woman and the girl, both from the Leyland area of Lancashire, were treated at the scene before being taken to hospital.
A man, who was also on the boat, is being treated at the Royal Lancaster Infirmary.
"Police are currently investigating the circumstances of this tragic incident and trying to establish the full facts about what has happened," a spokesman said.