NSW Police are required to investigate any fire in which more than $500,000 worth of property damage is caused.

UPDATE 1.30pm: ​ Witnesses have described the chaos that ensued after a houseboat caught fire just off the Murray River, setting off a chain reaction that caused millions of dollars of damage.

Jayne Bares, who was staying in a cabin overlooking the Deep Creek Marina, said she got up to make dinner about 6.20pm when she noticed smoke issuing from one of the houseboats.

She went down to the boat to investigate and found smoke coming from an air-conditioning unit, when a spa cover over it "exploded".

It did not take long for the fire to spread to other boats at the marina, in total claiming nine of them.

"It was so scary... You could not see the other end of the marina," Ms Bares said.

She said she initially tried to put out the fire with garden hoses, but they were ineffective - they even melted in the heat.

Ms Bares said the heat was so great that she could not stand at the front of the cabin, about 50 to 70 metres from the waterfront.

The situation was terrible, she said, and the boats at that end of the marina were among the best.

Moama resident Arnold O'Farrell is a friend of many of the boat owners and raced to the marina when he heard about the blaze.

By the time he got there, there were about six alight, "and they just kept snowballing".

"It was like a warzone, it was crazy," Mr O'Farrell said.

The fire blew up gas bottles, one of which he said landed in a paddock hundreds of metres away.

He said he frantically tried to save some of the boats and managed to push five of the houseboats, plus one barbecue boat, away to safety.

"The smoke was horrible, you couldn't breathe or anything," Mr O'Farrell said.

"Just black, black as the ace of spades."

Just the day before, he said, two or three of the boats were occupied, but on the night of the fire, they were all unoccupied.

One of the boat owners, who did not want to be named, told the Bendigo Advertiser he was told he had lost his boat with a phone call from his caretaker about 7pm.

"He said 'Your boat's gone' and I said 'Where?' and he said 'It's burnt, there's nothing left," the boat owner said.

The man had planned to sell his boat and had a few recent expressions of interest.

It was worth about $400,000 to $500,000, but was fully insured.

He said he had owned the boat for about four years and his family had filled it with a lot of memorabilia.

"It's a pity to see it go," he said.

"Just another end of an era."

But he remains optimistic, despite the stroke of bad luck he has recently suffered.

He worked with people with cancer and said that put him in a different mindset.

"It's a pity, but life goes on," he said.

UPDATE Noon: Witnesses have said the fire appeared to start in the first houseboat seen in the footage below.

They said they also saw smoke coming from an air-conditioner.

See more pictures in the updated gallery above, and view video of the scene here:

UPDATE 9.55am: Police are now investigating last night’s fire and a crime scene has been established after nine houseboats went up in flames.

NSW Police have been told the fire at a marina on the Murray River at Moama started on one boat and spread quickly to remaining eight.

Officers attached to Deniliquin Local Area Command established a crime scene and commenced an investigation this morning.

Inquiries into the circumstances are continuing.

Police are urging anyone with information to call Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page https://nsw.crimestoppers.com.au/

EARLIER: About 10 houseboats have been destroyed in a fierce fire at a marina on the Murray River at Moama.

New South Wales Rural Fire Service and Fire and Rescue NSW crews were called to Deep Creek Marina on Perricoota Road about 6.15pm on Thursday evening and found a number of houseboats well-alight.

NSW RFS Inspector Ben Shepherd said about 10 houseboats were destroyed, while about 10 were saved after they were cut loose from their moorings.

A small grass fire also broke out at the site as a result of floating embers.

Fire and Rescue NSW zone commander Stewart Alexander said conditions were difficult for firefighters, given the intensity of the blaze and the fact they could not get onto the vessels.

The fire was so great that the plume of smoke could reportedly be seen in Deniliquin.

Mr Shepherd said firefighters had the situation under control within about two hours, although the fire continued to burn into the night.

Mr Alexander said Fire and Rescue firefighters were at the scene until about 1.30am.

A small amount of fuel spilled into the water as a result of the fire.

Mr Alexander said the agency, with the assistance of Marine Rescue NSW, deployed booms to limit the spillage.

No one was injured during the incident.

Mr Shepherd said initial reports from people at the scene suggested an air conditioner on one of the boats might have been to blame for the fire, although RFS investigators would try to determine the cause.