At least 12 people have died and dozens have been rescued after the boat they were travelling in capsized during an attempted crossing of the English Channel, authorities say.

French Interior Minister Gerald Darmanin said 12 people were dead and rescue operations were under way on Tuesday to find two people still missing.

He said he would travel to the site, near the town of Boulogne-sur-Mer, later in the afternoon.

“Unfortunately, the bottom of the boat ripped open,” said Olivier Barbarin, mayor of Le Portel near Boulogne-sur-Mer.

Etienne Baggio, a spokesman for the French maritime prefecture that oversees that stretch of sea, said rescuers have pulled 65 people from the water.

Baggio described it as the deadliest migrant boat tragedy in the English Channel this year. Many of those on board didn’t have life vests, he said. It was not immediately clear how the boat ripped open or what kind of boat it was. Some attempt the crossing in rubber dinghies.

The maritime prefecture said the boat got into difficulty off Gris-Nez point between Boulogne-sur-Mer and the port of Calais farther north.

Sea temperatures off northern France were about 20 degrees Celsius (68 degrees Fahrenheit).

United Kingdom Home Secretary Yvette Cooper called the deaths “horrifying and deeply tragic”.

In a statement, Cooper criticised the “gangs behind this appalling and callous trade in human lives”, adding they “do not care about anything but the profits they make”.

At least 30 refugees and migrants have died or gone missing while trying to cross to the UK this year, according to the International Organization for Migration.

At least 2,109 people have tried to cross the English Channel on small boats in the past seven days, according to UK Home Office data updated on Tuesday.

The data includes people found in the channel or on arrival.