NSW Police and NSW Ambulance have finished giving an update on the incident in Ballina. 

You can look back on today's developments here in this story, or download the ABC News app for the latest updates.

Assistant Commissioner Armitage from NSW Ambulance is giving an update on the those rescued from the water.

"NSW Ambulance assessed a total of seven patients," he said.

"Unfortunately three of those patients were declared deceased on scene."

Three patients were transferred to Lismore Base Hospital with "varying injuries" minor in nature and are expected to make a "full recovery".

NSW Police say the water can be dangerous and can "turn quickly".

Superintendent McNulty urged people crossing a bar to wear lifejackets, and avoid crossing it in the first place if not trained. 

"Operate a vessel within your own skillset," he said.

Superintendent McNulty said the volunteers who lost their lives were from the Ballina region.

"What they did and what they tried to achieve by going out there ... to try save another vessel in distress and other mariners ... those people gave their lives up to help the people of New South Wales," he said of all six volunteers.

The Australian Maritime Safety Authority and the Westpac [Rescue Helicopter Service] at Lismore were also contacted to help with the search. 

"It was quite complex because we had the capsized and we still had the search and rescue operation running off the east coast there," Superintendent McNulty said.

"The Marine Rescue vessel capsized right on the bar as they were transferring between the river system and the ocean system," the superintendent said.

He said it was the "most appropriate" vessel to respond. 

"These vessels are specifically designed for the conditions in New South Wales, so they're very well built ... vessels.

"But last night was one of those nights where ... it was a difficult manoeuvre to go from the river system into the sea."

NSW Police said there was "no distress call" from the yacht. 

Superintendent McNulty says he believes it is a NSW-registered yacht. 

The vessel in distress hit the breakwall and broke up, the superintendent said.

A male in his mid-50s died, and is yet to be formally identified.

"He was not wearing a life jacket at the time of recovery so that will form part of the investigation," he said.

The 78yo and 62yo men who died were volunteers from Marine Rescue NSW. 

"They're out there saving the lives and responding to vessels in distress day in and day out," Superintendent McNulty said.

"Last night was a difficult situation ... it is a tragedy.

He commended their "commitment to the community, their commitment to keep people safe, their commitment to support New South Wales Police". 

"Six people went to save the life of another yachtsman at sea," Superintendent McNulty said.

He said that in the process of the rescue and in the "treacherous" conditions, their vessel capsized.

"Some of the marine rescue crew were trapped in the hull and ejected from the vessel and unfortunately, two lives have been lost."