Three lifeguards are being hailed as heroes after rescuing 36 children and four adults who got into trouble when a raised sandbank collapsed into the sea beneath them.

The party were plunged into cold waters at Tenby, west Wales, during the incident yesterday.

RNLI lifeguards patrolling Tenby South Beach had already spotted the group before they needed assistance and used rescue boards and fluorescent buoyancy aids to ferry them to safety, before performing first aid on a number of casualties.

The rescue happened at 4pm at a sandbank known locally as the White Back at the right side of the beach outside of a red and yellow flag zone.

An RNLI spokeswoman said that the group were walking along the sandbank, which liquefies and gets swept away as the tide comes in, when they suddenly found themselves out of their depth in “treacherous waters.”

At the time of the incident, the group was making its way back to the shore after receiving a warning from one of the RNLI patrol.

Two members of the patrol, Adam Pitman and Jon Johnson, entered the water with rescue boards and tubes and brought the party safely to shore while another lifeguard, Coral Lewis, radioed the Coastguard.

The spokeswoman said that first aid was performed on one person suffering from a “hypothermic asthma attack” and on another who had a “hypothermic secondary drowning”.

“Six of the group’s lives would have been lost had the lifeguards not intervened,” the spokeswoman added.

The children, who were aged between 12 and 15, were of varied swimming ability. They were staying at the nearby Kiln Caravan Park, which leads on to the beach.

Dave Miller, Coastguard Sector Manager in South Pembrokeshire, said: “The three RNLI lifeguards did a superb job today.

“If not for their fast response times and the methods they used at the scene, lives would have been lost.”