Helicopters and lifeboats swooped to the English Channel off the coast of Kent in southern England to rescue a small boat that capsized in the freezing water, killing four people, authorities said Wednesday.

Prime Minister Rishi Sunak confirmed in comments before Parliament there was a loss of life but offered no specifics. Home Secretary Suella Braverman was expected to update the House of Commons later Wednesday.

“After a coordinated search and rescue operation led by HM Coastguard, it is with regret that there have been four confirmed deaths as a result of this incident. Investigations are ongoing and we will provide further information in due course,” the government said in a statement. “This is a truly tragic incident.”

The U.K. Maritime and Coastguard Agency coordinated a rescue operation involving the Royal Navy, border officers, Kent police and the French navy. The Royal National Lifeboat Institution also dispatched boats.

The South East Coast Ambulance Service said it sent help at about 3:40 a.m. local time to help the coast guard.

Thousands of migrants have relied on small boats to cross the Channel in hopes of receiving asylum in the U.K. The British government has been under pressure to stop people from paying smugglers to cross some of the world’s busiest shipping lanes in flimsy vessels.

But the number of people who choose to make the dangerous voyage continues to climb. Some 44,000 people made the journey so far this year, compared to 23,000 last year and 8,500 in 2020, according to government figures.

Sunak pledged Tuesday to clear a backlog of asylum-seeker applications and announced new measures aimed at curbing the number of migrants reaching the U.K. by crossing the Channel.

Sunak said he planned to introduce legislation early next year to ensure people who arrive illegally cannot remain in the country.

The prime minister said he was adding hundreds of workers to process asylum claims and to clear the backlog, estimated at more than 143,000 pending applications, by the end of 2023. The extra staff will also focus on the swift removal of Albanian migrants who have arrived via the Channel in increasing numbers, Sunak said.