Six people, including three children, were killed after a helicopter carrying a family of Spanish tourists crashed into the Hudson River in New York on Thursday, authorities said.

Three children and three adults were onboard the helicopter at the time of the crash. Five of the individuals were from Spain and the sixth person was the pilot, New York City Mayor Eric Adams told reporters.

"Our hearts go out to the families," he said.

New York Police Commissioner Jessica Tisch said the identities of the victims would not be released until the families were notified. The cause of the crash is under investigation.

Video footage posted to social media appears to show the helicopter falling out of the sky upside down and splashing down in the Hudson River.

Officials said the helicopter lost control soon after turning at the George Washington Bridge to move along the New Jersey shoreline.

• What we know about the Hudson helicopter crash

The first calls of the crash came around 15:17 EDT (20:17 GMT) and rescue boats were launched immediately, New York's Fire Commissioner Robert Tucker said.

"Swimmers were in the water shortly after the call," he said.

Once on the scene, rescuers started searching the water for victims or survivors and initiated "immediate life-saving measures" but the efforts were unsuccessful.

Four victims were pronounced dead on scene, the other two victims were pronounced dead at an area hospital, officials said.

The part of the river where the helicopter crashed is near the West Side of Manhattan. The surrounding area is a neighbourhood called the West Village, a trendy area known for its shops and dining, also near the main campus of New York University.

A BBC journalist who was at the top of the World Trade Center at the time of the crash said there were about a dozen boats surrounding the site of the crash.

The Federal Aviation Administration (FAA) said the investigation into the crash of the Bell 206, a two-bladed helicopter, would be led by the National Transportation Safety Board.

The Bell 206 is commonly used by sightseeing companies, television news stations and police departments.

This was one of the deadliest helicopter crashes in New York City since 2018, when a tourist helicopter crashed into the East River.

All five passengers drowned, and only the pilot survived. In 2009, a helicopter carrying Italian tourists collided with a private plane over the Hudson River, killing nine people.