At least three people died and one person is missing after a 16-meter tourist boat capsized and sank on Lake Maggiore in northern Italy Sunday evening.

Divers backed by a helicopter continued to search for the missing person.

An air ambulance, several emergency vehicles, and firefighters, as well as the Coast Guard and the police were involved in the rescue and search.

The National Fire and Rescue Service said 20 people managed to swim ashore or were rescued by other boats, and five of them were taken to area hospitals for medical attention.

Rescue efforts, however, were slowed by heavy rain and darkness, authorities said.

Italian media reported that the boat was carrying 24 people, including passengers and crew. The passengers were celebrating a birthday when a violent storm suddenly developed over the lake and strong winds overturned the boat. All the passengers ended up in the icy waters of Lake Maggiore.

Unconfirmed reports in local media said that the passengers were British, Italian, and Israeli nationals.

Lake Maggiore is located on the south side of the Alps on the border between Italy and Switzerland. It is a popular destination for tourists.