aTwo men have drowned and a man is missing after getting into trouble at a beach near Coffs Harbour on the New South Wales mid-north coast.

Key points: Surf was described by a witness as "ferocious"

Surf was described by a witness as "ferocious" Three teenagers were taken to Coffs Harbour Hospital for observation

Three teenagers were taken to Coffs Harbour Hospital for observation Police would be recommending bravery awards for some involved in the rescue

Police said at about 6:15pm on Monday a group of six people — including three teenagers — began to struggle in the surf while swimming at Moonee Beach, north of Coffs Harbour.

Moonee Beach is an unpatrolled beach and authorities believe the group was likely swept out by a strong rip.

Surf Lifesaving NSW said the group was 300 metres offshore by the time the call for help came.

Off-duty Coffs Harbour lifeguards used rescue boards during the operation, which was also attended by the Westpac helicopter.

A third man, aged 28, remains missing.

The search resumed this morning after being suspended due to bad light last night.

Two girls, aged 13 and 17, and a 15-year-old boy were also removed from the water and were taken to Coffs Harbour Hospital for observation.

They are all in a stable condition.

Six people from western Sydney got into trouble in surf at Moonee Beach. ( Supplied: NSW National Parks )

Police said all six are believed to have known each other and are from western Sydney.

Witness Michelle Collard said the two men pulled out of the water were not in a good way after struggling in the "ferocious" surf.

"They had oxygen masks on their faces and they were absolutely exhausted, you could see that they had put up a good struggle just trying to get themselves out of the water."

She said locals pitched in to help search for the missing man, while others assisted with CPR.

Coffs Coast Lifeguard Greg Hackfath, who is assisting with the rescue operation, said extensive rainfall had almost certainly contributed to the strong waves.

"The amount of water that was coming out of Moonee Creek was pretty substantial," Mr Hackfath said.

"I don't know how much rain they had up this way, but the creek was certainly brown and [had] a lot of floodwaters coming out it."

Mr Hackfath said strong winds had also caused the coastal waves to swell.

"It was pretty horrible conditions. You couldn't have asked for much worse conditions than what it was."

He said Moonee Beach was difficult to access and was a problem spot due to the creek and river mouths causing rapid torrents.

Inspector Brendan Gorman from Coffs Harbour Police said rescuers and volunteers conducted "some really brave actions".

He said police would be recommending bravery awards for some involved in the rescue.

"One particular lifeguard went out quite some distance, we believe three or four or 500 metres out to bring one person back."

Surf Lifesaving NSW CEO Steven Pearce said the tragedy highlighted the importance of swimming at patrolled beaches and understanding how to identify rips.

"Our thoughts and hearts go out to the family of the victims and to the brave lifeguards that responded and tried valiantly to save everyone," Mr Pearce said.

"An event like this unfolding so close to the festive season only magnifies the grief and devastation."

The Westpac Rescue Helicopter has dropped a dye pack to determine the direction of the current and tide to determine the likely location of the missing man.

A memorial is being organised for the dead men at Lakemba Uniting Church tomorrow at 5:30pm.