Police in Australia are monitoring up to 30 known arsonists as bushfires continue to burn in the south-east.
Firefighters have said the fires that have hit the area so far have been the result of either accidental or deliberate human activity.
The situation was exacerbated by a return of hot dry weather on Tuesday.
More than a dozen homes have been destroyed in the last few days, and an ambulance worker died helping people escape to an evacuation centre.
Rural Fire Service Commissioner Phil Koperberg said monitoring those with a history of arson was necessary at the moment.
"It's a very appropriate measure to take, given the degree of public threat," the Associated Press quoted him as saying.
"Whether it's the stupidity of [throwing away] cigarette butts or a wanton act of criminality in deliberately starting a fire, there are very tough penalties," he said.
The Rural Fire Service urged residents to be vigilant amid the dangerous weather conditions, and report suspicious behaviour and fires as soon as they were aware of them.
Parts of New South Wales, including the wine-producing Hunter Valley region, have been put under a total fire ban and almost 30 fires were still burning in the state on Tuesday, the Sydney Morning Herald reported.
Australia's south-eastern corner is one of the world's most fire-prone regions.