Emergency services are set to resume their search for a group of people feared missing in the desert north-east of Broken Hill for almost one day.
Police said a woman called triple-0 about noon on Tuesday saying she was lost about one hour from the mining town. Her line dropped out and emergency services were unable to reach her again.
After an extensive search lasting several hours, police said her call was traced to Mutawintji National Park, which is about 150 kilometres north-east of Broken Hill.
A vehicle was spotted after a flyover but when rescuers reached it by land about 8pm, no one was found, police said.
Barrier Local Area Command officers spoke to the woman's family and she was believed to be travelling with one or two others.
The search was suspended later due to poor light and will resume this morning. The State Emergency Service and local officers would be involved in the search.
The national park, which is about 800 kilometres west of Sydney, is described by NSW National Parks as located in a "ruggedly beautiful desert region" dominated by the Bynguano Ranges. Visitors can explore the park using walking trails, by four-wheel-drive and are allowed to camp overnight.
The temperature in the park in November ranges between 18 to 33 degree Celsius, with average monthly rainfall of about 20mm, National Parks said.
Temperatures in the areas near Broken Hill were about 10 degrees or above last night, Bureau of Meteorology forecaster Chris Webb said. The maximum temperature in Broken Hill on Tuesday was 28 degrees, he added.
Visitors to the park are advised to bring adequate food supplies and to boil the available bore water. They are also advised to stay with their vehicle if it breaks down, inform others of their itinerary, register with the ranger, carry extra supplies and to prepare for extremely hot conditions during the summer.