Two people have died in a major bushfire north of Adelaide and there are unconfirmed reports of a third death, South Australian Premier Jay Weatherill says.

Fire crews are working through the night battling the blaze, which is burning out of control.

One body was found in a paddock and a body was also found in a car in north east Adelaide.

The unconfirmed report is of a death near Freeling after a car was reported to have hit a tree.

“Our priority will be to access these sites safely and, of course, to notify the next of kin,” Weatherill said.

Weatherill also confirmed at least three people who were helping fight the fire have been taken to the Royal Adelaide Hospital with severe burns.

We also know that there are many homes, sheds, crops and livestock losses due to the active fire front, I can’t give you exact figures at this point," Weatherill said.

Properties in Tarlee, Freeling and Kapunda have been affected by the blaze, which had burned more than 85,700 hectares on Wednesday.

An emergency warning on Wednesday night said the main fire activity was around Kapunda, and there remained potential for structures to be impacted.
The fire front was about 40 kilometres wide.