There are fears that a migrant remains missing at sea after a boat got into difficulty in the English Channel.
Three people suffering from hypothermia have been taken to hospital but French authorities say there may have been a fourth person on board.
Local media have reported that the boat capsized off the coast of France.
The Dover Strait is the world’s busiest shipping lane and features dangerous waters.
Crossing the English Channel aboard small boats is perilous and has claimed several lives, including those of a Kurdish-Iranian family last year.
The alarm was raised late on Tuesday night and led to a search effort at sea.
At around 10.30pm, firefighters aided two Sudanese nationals who were suffering from hypothermia.
They had been on board a boat trying to reach the UK but had got into trouble, French authorities told the PA news agency.
As they were assisted and taken to a hospital in Calais, the pair reported that three or four people had been aboard the vessel.
A significant search and rescue operation was launched that night to try and find any other survivors from the failed crossing.
A third person was discovered, also suffering from hypothermia, close to the port of Calais and was taken to hospital.
French authorities said searches at sea for a possible fourth person continued but to no avail.