NSW police are searching for a missing man and child thrown into the ocean after their boat capsized in the Illawarra region on Saturday night.

Wollongong Chief Inspector Darren Brown said police received a call that people were in the water off Bulli Beach on Saturday.

A police helicopter and three rescue boats searched the waters and found an upturned vessel.

“During that search, they located two persons in the water, alive, but very cold and exposed to the elements,” Chief Inspector Brown said.

“They recovered those people and brought them to shore.”

He said two men in their 30s were taken to hospital for treatment.

Police began searching the waters off Bulli Beach after reports people were in the water. Photo: ABC

Chief Inspector Brown said conditions on Saturday night were not ideal.

“We’ve had big seas at the moment, but I’d say it’s hazardous and dark and there’s waves out there,” he said.

“Plus it’s a point with reef and the area we’re searching at the moment has got a lot of reef.”

The area is known to local surfers as Peggy’s, with the rocky reef also popular for fishing.

Police say the upturned boat was estimated to be between 4 to 5 metres in length, but they have been unable to find out why

Police Helicopter, water police, Marine Rescue NSW and a surf lifesaving boat have been involved in the search.

Chief Inspector Brown said the rescuers would continue the search as long as possible on Saturday night and would resume in the morning if they could not find the missing people.

-ABC