Updated | 20 people - including one who was unconscious - saved in mass rescue at North Cronulla

Volunteer lifesavers and council lifeguards pulled 20 people from the surf in a mass rescue at North Cronulla beach on Sunday.

One man in his 50s was unconscious when he was picked up by the Elouera IRB (inflatable rescue boat) and taken to Elouera beach.

He regained consciousness after defibrillation and was taken by ambulance to St George Hospital in a stable condition.

A teenager and another person in their 20s were given oxygen on North Cronulla beach before being taken by ambulance to Sutherland Hospital. Both were conscious, and their condition was not thought to be serious.

The incident occurred just after 3pm when the beach was packed in glorious sunny weather.

Michael Bonnici, of the Wanda club, who was the Bate Bay surf life saving clubs duty officer on Sunday, said "a flash rip occurred and people started panicking and they got sucked out to sea".

Mr Bonnici said the rescues were carried out by a surf life saving jet ski and IRBs from North Cronulla and Elouera clubs and patrol members on rescue boards and with tubes, along with council lifeguards using a jet ski.

"Someone would have lost their life if these people didn't do what they did today," he said.

Mr Bonnici said the surf life saving jet ski operator Nicole Krite did "a massive job" and the council lifeguards who worked on the most serious patient also deserved special mention.

In a Facebook post on Monday, the North Cronulla club praised the "tremendous" joint effort.

"North Cronulla wishes to thank and acknowledge the efforts of all our Patrol 12 members led by patrol captain Megan Kessey and vice captain Tulley Lane, who were on duty on Sunday".

"These volunteers exemplified the SLS motto of Vigilance & Service.

"Yesterday, lives were saved at North Cronulla in a joint mass rescue by North Cronulla Surf Life Saving Club, Elouera SLSC, Sutherland Council Lifeguards and Surf Life Saving Sydney Support Operations team. Tremendous effort by everyone involved - thank you

"We appreciate the impact events such as these have on our first responders, all those involved and of course the wider community."

A NSW Ambulance spokeswoman said one person aged in their 50s was taken to St George Hospital and two others to Sutherland Hospitals.

All three patients were conscious, she said.

The spokeswoman said the first call came in at 3.10pm and multiple ambulance units rushed to the beach.

North Cronulla and Elouera beaches were closed following the mass rescue. Wanda had been closed earlier.

North Cronulla has had dangerous rips running throughout January and there have been several earlier rescues, with regular beach closures.

On Australia Day eve, Sutherland Shire Council lifeguards revealed there had been a series of rescues in January at North Cronulla beach.

"North Cronulla beach currently has a large rip/dangerous current in the centre of the beach," they posted on Instagram.

"The beach has been closed all week due to this public safety hazard and risk.

"There have been numerous rescues and near misses both during patrol hours and also after hours (we would like to thank our surfing and coastal community for helping here)."

It is understood one rescue took place about 8pm on Thursday January 12 when two men were taken out in a rip. A board rider and three other men without boards went to their aid and brought them safely to shore.

Another incident occurred about 7.15pm on Monday January 23 when board riders, including Harrison Martin and Kirk Jenkins, saved four men who became caught in a rip.