It happened on Lough Foyle at Quigleys Point when they were driving back from a day trip to Derry.
The mother of the children managed to escape the car and get help.
The bodies of a 49 year old man, a 14 year old boy and a 6 year old girl have since been recovered.
Damian Dowds from the Inishowen Independent says the weather may have been a factor in the accident:
