Dozen houses destroyed, 20 more feared lost in SA bushfires

South Australia Premier Jay Weatherill says a dozen houses have been destroyed and 20 more are feared lost in the still-burning Adelaide Hills bushfire.

Authorities will seek to re-open fire-affected areas to the public soon but there are risks of falling trees.

Mr Weatherill said a fire truck had been destroyed by a falling tree yesterday evening.

Six firefighers have also been hurt during the battle against the blaze, as part of a total of 22 people who suffered minor injuries.

The warning on the fires has been downgraded to "watch and act", but residents are still warned to be wary of conditions changing.

Mr Weatherill said cooler temperatures meant firefighters were better placed to act on containment, with aerial vehicles able to be used today after being grounded yesterday.

Crews from NSW and Victoria will also join their South Australian counterparts on the front lines.

While the Country Fire Service works on containing the blaze and preventing it from reaching threatened towns on its north and south edges, including Williamstown and Inglewood, the government is contacting homeowners and families believed to have lost residences.

Mr Weatherill said emergency grants were available for people in need of immediate necessities.

Others who had suffered loss or trauma can contact the South Australia Bushfire Recovery Hotline on 1800 302 787.