French police officers patrol on the beach in the searcher migrants in Wimereux, northern France, today. Several migrants died and others were injured today when their boat capsized off Calais in the English Channel as they tried to cross from France to Britain, authorities said. British and French authorities were searching the area using helicopters and coast guard vessels, according to the French maritime agency for the region. (AP Photo/Louis Witter, File)

PARIS (AP) — A boat carrying migrants capsized today in the English Channel while attempting to cross from France to Britain, killing an unspecified number of people, French authorities said. Dozens were feared dead.

Although officials offered few confirmed details, it appeared to be one of the deadliest days in the channel in recent memory. Britain’s prime minister convened a meeting of the government’s crisis committee, and France’s interior minister rushed to see survivors in a Calais hospital. The two governments have been at odds over how to prevent the increasingly dangerous migrant crossings.

A French naval boat spotted several bodies in the water around 2 p.m. and retrieved an unknown number of dead and injured, including some who were unconscious, a maritime authority spokesperson said.

Three French patrol boats were joined by a French helicopter and a British helicopter in searching the area, according to the French maritime agency for the region.

Jean-Marc Puissesseau, head of the ports of Calais and Boulogne, told The Associated Press that he spoke to one of the rescuers, who said as many as 30 people had died.

The rescuer brought some of the bodies to the Calais port, Puissesseau said.

“Traffickers are assassins,” he said. “We were waiting for something like this to happen.”

Franck Dhersin, a vice president for the surrounding region, tweeted that 24 bodies were pulled from the water after a boat carrying about 50 migrants sunk. But he did not provide a source, and maritime authorities and local police said the total number of dead remained unclear.

While deaths are occasionally reported on the crossing, such a large number of people losing their lives in one boat would be exceptional.

The victims’ nationalities were not immediately released. People fleeing conflict in Afghanistan, Iraq, Eritrea and Sudan have been among those gathered along towns in northern France seeking to cross to Britain.

Prime Minister Boris Johnson was holding a meeting of the government’s crisis committee, COBRA, in response to the channel tragedy, his office said.

“Strong emotion after the drama of numerous dead in the sinking of a boat of migrants in the channel,” Interior Minister Gerald Darmanin tweeted. He slammed migrant smuggling networks that organize such journeys and headed to a Calais hospital to see the victims.

The number of migrants using small boats to cross the channel has grown sharply this year, despite the high risks that are worsening in autumn weather. More than 25,700 people have made the dangerous journey in small boats this year — three times the total for the whole of 2020.

With changeable weather, cold seas and heavy maritime traffic, the crossing is dangerous for the inflatables and other small boats that men, women and children squeeze into.

French and British authorities have picked up thousands of migrants off both the French and British coasts in recent weeks in scores of rescue operations. Deaths occasionally occur, but are rare.