This is the moment a rescue helicopter plunged into the sea in front of horrified beachgoers, as it attempted to rescue a man caught in a dangerous current.

The shocking footage was caught on the mobile phone of a man on Rio de Janeiro's Copacabana beach.

helicopter

The helicopter plunged under the water in front of terrified tourists

A wave caught the helicopter as it neared the water, pulling it under. The crew and the swimmer were rescued and dragged out by local surfers and others on the beach.

Officials said the helicopter has suffered a mechanical failure.

Eyewitness Alfonso Peireira told the BBC: "The crew were saving the lives of people who recklessly swam into the waves. The sea has been raging yesterday and today."

Warning signs were up on the beach cautioning against swimming in current conditions.