A humanitarian crisis and looming horror fire conditions have prompted authorities to begin a 24-hour race against time to move thousands of people from the south coast of New South Wales.

About 50,000 homes are without power, phone networks are down, fuel is running low, major supermarkets are closed and people are queuing up to three hours to get food.

People queue to buy non-refrigerated food from Batemans Bay Coles. Picture: John Grainger

NSW Police opened the Princes Hwy northbound on Wednesday night as a window for the thousands of holiday-makers who have been stranded from Milton to Batemans Bay to head home.

The Kings Hwy across to Canberra remains impassable because of bushfires as service stations either could not open because of lack of power or ran out of fuel.

The Rural Fire Service issued a map last night of where tourists were being asked to leave, highlighting an area 250km long from Batemans Bay to the Victorian border, and 160km wide.

With seven people dead and 176 homes lost, the unprecedented onslaught of fires laid waste to communities all along the coast, such as Lake Conjola where 89 homes were destroyed, and there was no ­mobile reception and little running water.

"It was like a war zone. Or something out of a movie," local Paul Murphy, 41, said.

Bushfire-affected residents line up to use public phone. Picture: Jade MacMillan/ABC

HMAS Choules, which specialises in responding to humanitarian crises, was carrying fresh water, medical aid, food and temporary shelter as it left Sydney on Wednesday heading for the south coast and Mallacoota in ­Victoria, depending on greatest need.

The NSW government is in a race against time to open roads and get the thousands of people moving, with Premier Gladys Berejiklian warning that after milder conditions, extreme fire conditions will return on Saturday.

"We're assuming that on Saturday weather conditions will be at least as bad as they were (on Tuesday)," Ms Berejiklian said.

People shopping in the dark at a supermarket in Narooma. Picture: Jade Macmillan/ABC

She said communities needed to prepare for the possibility of more ­fatalities.

"I do want everyone to brace themselves," she said, while visiting Batemans Bay where people have been left sleeping in their cars.

"Many people who have been here for decades are just completely shocked that the fire reached as far as it did."

People queued for more than three hours to get into Coles at Batemans Bay which was running on back-up power, unable to sell refrigerated or frozen items and with a skeleton staff as many employees could not get to work because of road closures.

Woolworths stores at Batemans Bay, Moruya and ­Narooma remained closed.

NSW Premier Gladys Berejiklian holds a press conference at the NSW Rural Fire Service headquarters on Wednesday. Picture: AAP

NSW Police Deputy Commissioner Gary Worboys said large swaths of the south coast between Nowra and Batemans Bay would most likely be without power and some telecommunications for an ­"extended period".

He asked for patience as police and utility providers tried their best to get services restored.

"It's a tedious task. There is no magic wand to wave across this and fix it in a short amount of time," he said.

"We have to make sure that when we restart the power, we do that with safety and confidence, that it will ­remain on. People need to understand this is not a simple or easy task."

Carrying what Defence Minister Linda Reynolds ­described as "lifesaving supplies", HMAS Choules was expected to arrive at Mallacoota in Victoria's East Gippsland region at 10am on Thrusday, as was Navy-contracted MV Sycamore.

Also on board is a MRH-90 Taipan helicopter, which does search and rescue operations, as well as a medical team, amphibious beach team and landing craft.

Google street view of Sylvan St Malua Bay before the bushfires.

Both ships will be able to evacuate people from the shore - without docking. Choules can accommodate up to 700 people.

"I have authorised the ­deployment of the Australian Defence Force's key humanitarian assets to the NSW south coast and East Gippsland, including the ADF's online humanitarian assistance and disaster relief ship, the HMAS Choules," Ms Reynolds said on Wednesday.

"Along with air assets ­deployed to the region, they will be available to assist with providing lifesaving supplies, conducting evacuations and assisting with fire reconnaissance in close co-ordination with our emergency services," she said.

"Australians can be assured that the ADF is providing extensive support to our emergency service personnel, as it has since early November … and will continue to do so."

Cobargo resident Shona Taranto, who lost here small business in Main St, is comforted by Tim O'Mearo. Picture: Gary Ramage

On Wednesday, families told how they split up to ensure their children were safe.

At Lake Conjola, Chris and Nikki Morris sent their sons Taj, 15, and Alex, 9, to the lake on Tuesday to keep them away from the blazes that raged through the area.

"We just wanted the kids to be safe so we sent them down to the water and Chris and I stayed to defend the home," Ms Morris said.

"After that, it was just black, you could barely see the sun and the fire roared through the street. We were running around hosing, pouring buckets of water wherever we could."

Conjola residents Nikki and Chris Morris sent their sons Taj and Alex to the water while they battled to save their family home. Picture: Darren leigh Roberts

They did not ­escape the wrath of the blaze with fencing destroyed and their backyard scorched.

More than 1000 homes have been lost in NSW.

Melbourne couple Nadine Pohl and Matt Jolly waited an hour to use a pay phone a Narooma to tell their family they were safe. Picture: Gary Ramage