The women, aged about 20, were aboard a small boat carrying 82 people, Christophe Marx, a regional government official, told reporters.
The boat set out to sea during the night from Saturday to Sunday, but “the engine wouldn’t start” and the boat began to drift, Marx said.
Seventeen people were rescued at sea and taken to the port of Boulogne-sur-Mer.
The boat with the remaining 65 people on board eventually ran aground on a beach near Neufchatel-Hardelot, about 12 kilometres (seven miles) south of Boulogne-sur-Mer, he said, adding that the victims had been found “dead inside the boat”.
Thirteen people with moderate injuries and three others with serious wounds, including burn victims, were taken to hospital.
They were “being treated and will be interviewed by border police to determine who is responsible for this crossing”, Marx said.
He said an investigation would confirm the nationality of the victims.
This is the third such tragedy in just over a month at the French-British border.
On April 1, two migrants died off the coast of Gravelines in northern France while attempting to reach the United Kingdom.
On April 9, two men and two women died, swept away by the currents.
In 2025, at least 29 migrants died at sea in the region, according to an AFP tally based on official French and British sources.
Britain and France last month signed a new three-year deal on security operations to stop the crossings.
France will increase the number of police and gendarmes patrolling the coast while the British government will increase its contribution to the cost.
According to French officials, the number of arrivals in Britain so far this year has been drastically cut from 2025.
