"What do you say about anyone like that?" Rudd said. "There's no words to describe it, other than it's mass murder."
Police have sealed off at least two towns - Marysville and Kinglake - where dozens of deaths occurred - setting up roadside checkpoints and controlling access to the area.
Victoria Police Commissioner Christine Nixon said specialist fire investigators were on the ground at one fire site, in Churchill, east of Melbourne, and would go to others.
Kinglake is "where the most deaths are, but wherever a death has occurred we investigate that as a crime," Nixon told Australian Broadcasting Corp. radio.
Anyone found guilty of lighting a wildfire that causes death faces 25 years in prison in Victoria.
At least 750 homes were destroyed. Officials said both the tolls of human life and property would almost certainly rise.
While weather conditions have eased since Saturday's inferno, more than one dozen fires still burned in Victoria and gusting winds threatened to fan them toward towns not previously hit. Forecasters said temperatures may rise again later in the week.
Blazes have been burning for weeks in the southeastern state of Victoria but turned deadly Saturday when searing temperatures and wind blasts created a firestorm that swept across the region. A long-running drought in the south - the worst in a century - had left forests extra dry and Saturday's fire conditions were said to be the worst ever in Australia.
From the air, the landscape was blackened as far as the eye could see. Entire forests were reduced to leafless, charred trunks, farmland to ashes. The Victoria Country Fire Service said some 850 square miles (2,200 kilometers) were burned out.
Only five houses were left standing out of about 40 in one neighborhood of the hard-hit Kinglake district that an Associated Press news crew flew over. Street after street was lined by smoldering wrecks of homes, roofs collapsed inward, iron roof sheets twisted from the heat. The burned-out hulks of cars dotted roads. A church was smoldering, only one wall with a giant cross etched in it remained standing.
Residents were repeatedly advised on radio and television announcements to initiate their so-called "fire plan" - whether it be staying in their homes to battle the flames or to evacuate before the roads became too dangerous. But some of the deaths were people who were apparently caught by the fire as they fled in their cars or killed when charred tree limbs fell on their vehicles.
