Fourteen bushfires burning across southern Australia have killed two people and thousands of animals, and destroyed 16 homes, and authorities on Thursday said they feared the toll could rise.

The fires, which stretch across 210 km (130 miles), broke out on Wednesday in heat-wave conditions and quickly burned across farmlands, forcing residents to flee and others to frantically try and save their homes and livestock.

"It was just the intensity of the fire and the speed. We tried to put it out. You just couldn't put it out," farmer John Lush told Australian Broadcasting Corporation.