A rescue helicopter is on its way to Crescent Head on the NSW mid north coast following reports that multiple people were in trouble in the water.
A Westpac Rescue Helicopter spokesman said initial information was that an unknown number of people had been washed from a rock shelf by a freak wave.
A NSW Ambulance spokesman said paramedics are at Goolawah Beach at Crescent Head with 14 patients suffering various injuries, mainly cuts and abrasions, from rough surf.
Paramedics were called to the tough-to-reach location about 12.30pm, he said.
A Surf Life Saving NSW spokesman said a large group was at an isolated rock platform south of Crescent Head known as Big Nobby when a wave washed the group against rocks about 12.40pm.
He said there were reports of at least five injuries, including a broken shoulder and a suspected head injury.
It was unclear whether the group was already in the water when the wave struck.
"Our reports were that at least some of them were (in the water) and were able to get out," the spokesman told AAP.
Local volunteer lifesavers and paid lifeguards attended but it was deemed impractical to conduct a water extraction, and an ambulance helicopter was called.
"It's expected that the vast majority of the people involved will be able to walk out," the spokesman said.
"But as it's an isolated location it is obviously quite challenging."