Three vessels have sunk after a fire ripped through luxury yachts moored at a Sydney Harbour marina overnight.

Emergency services were called to the Spit Marina, off Mosman in Middle Harbour, in Sydney at 3.30am on Friday following reports of a fire, New South Wales police said in a statement.

On arrival, emergency services found a yacht “well alight”, police said. Four people were evacuated from the vessel.

One woman was treated for smoke inhalation by NSW Ambulance paramedics before she was taken to hospital in a stable condition.

Adam Dewberry, a Fire and Rescue NSW superintendent, told media on Friday that once the fires were extinguished the area would undergo decontamination.

“We’ve got three of these large yachts that have sunk,” Dewberry told Nine’s Today show. “We’re now moving into the hazmat stage, where we’re working with the Port Authority of NSW to get booms around to make sure that we capture all of that contamination.

“There is a lot of debris on the water and also to collect fuel and oil, which does float to the top, fortunately. And then, of course, investigations will commence by the police with fire rescue assisting.”

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Dewberry said the outcome of the fire could have been significantly worse.

“Out here, there’s dozens of boats and yachts and a lot of money, and people are living on some of these vessels as well. But fortunately, the actions of firefighters and fire rescue when they arrived cut [the fire] off. And the NSW ports authority, their fire tug that arrived, was able to cut it off,” Dewberry said.

“Yes, we’ve lost three vessels with a fourth one pretty badly damaged, but we could have lost many more of these yachts out there.”

Police said initial inquiries had been conducted and the fire was not being treated as suspicious.

The marina at the Spit is one of six in Sydney recommended by Superyacht Australia for berthing of yachts 30 metres or longer.

Its website describes the facility as offering “106 secure wet berths for vessels up to 50m, including dedicated superyacht berths. It’s one of Sydney’s premier spots for luxury berthing and on-water convenience.”

One northbound lane of Spit Road was closed on Friday morning.