A man was being treated in a hospital after the tragedy on Lake Windermere, the Daily Mirror reported. The boat was docked at a jetty in Bowness, a popular tourist spot on England's most famous lake.
All three people on board were airlifted to the Royal Lancaster Infirmary, where the 36-year-old woman and the girl died, The Guardian reported. The mother and daughter were from Leyland in Lancashire.
Duncan Bannatyne, a businessman and panel member on the reality TV show "Dragon's Den," witnessed the tragedy and sent a picture via Twitter with the comment: "Tragic accident over there I am afraid."
Cumbria police said the report that three people on the boat were having trouble breathing came in around 4 p.m.