At least four migrants — including children ages 5 and 8 — died Tuesday when their boat capsized while crossing the English Channel to Britain, according to French authorities.

Fifteen migrants who were also on the overturned boat were rescued, the regional administration for the Nord region said.

Among the dead were the 5- and 8-year-old children, an adult woman and adult man.

The administration said the death toll so far is preliminary pending further searches in the area.

Five vessels and a Belgian helicopter were mobilized after the migrant boat was reported in distress off the coast of Dunkirk, according to the regional French maritime agency. It said earlier that 18 people were rescued and receiving treatment in hospitals in Calais and Dunkirk.

The discrepancy in numbers was not explained.

An investigation into the deadly crossing has been launched by the Dunkirk prosecutor.

French maritime officials routinely rescue migrants — who use northern France as a launching point to sneak into Britain — trying to cross the Channel and warn against the dangerous trip.

Last year, French authorities said at least four people died trying to use small boats to cross the Channel, known for its high winds, strong currents and heavy maritime traffic.

In a statement, British Home Secretary Priti Patel said she was “truly saddened to learn of the tragic loss of life in French waters this morning.”

“We are in touch with our French counterparts who are leading on the response and have offered whatever support they need as they investigate this incident,” she added. “This tragic news highlights the dangers that come with crossing the Channel and I will do everything I can to stop callous criminals exploiting vulnerable people.”

With Post wires