At least two people have died and 15 people have been taken to hospital, five of them in serious or critical conditions, as fire crews continue to battle a devastating bushfire in South Australia’s Pinery region.

The fire did not increase in size overnight and cooler winds are expected to ease conditions today.

The Country Fire Authority has warned the blaze is still uncontrolled and the area remains unsafe.

South Australian premier Jay Weatherill confirmed “grave fears” were held for more people, with the full cost of the blaze still to unfold.

“We can’t be sure we have identified every single person in the fireground,” Mr Weatherill told a press conference this morning.

An updated watch and act message has been issued by the SA CFS.

Latest updates:

• A 56-year-old woman was killed in a car in Hamley Bridge yesterday, while the body of 69-year-old man was found in a paddock in Pinery. Their families have been notified.

• Thirteen people remain in hospital, five of whom are in serious or critical conditions. One of those has burns to around 80 percent of their body. At least two of those injured were people fighting the fires.

Property owners Jim and Lorraine inspect their destroyed house near Roseworthy in the mid-north of South Australia. (AAP)

• At least 16 homes and another 22 outbuildings have been destroyed.

• More than 200 firefighters are on the ground, with 350 more from Victoria set to arrive today.

• The fire perimeter has not expanded since midnight, although fires are still burning in the area.

At least 16 homes have been burned down. (9NEWS)

• A piggery was lost, with an estimated 2000 sows killed.

• A joint investigation team has been established.

• The cause of the fire remains unknown. Crime scene investigators will continue to examine that area today.

The fire has burned about 85,700 hectares. (9NEWS)

WATCH AND ACT MESSAGE FROM THE CFS:

The Pinery Fire in the State's Mid North remains a going fire with sporadic fire activity across the entire fire-ground.

Fire activity remains around many townships including Owen, Hamley Bridge, Tarlee, Freeling, Wasleys, Kapunda, Greenock and surrounding areas.

A significant volume of smoke can be expected around the fire-ground and may have an impact on visibility in surrounding areas and there remains the potential for structures to be impacted due to ongoing ember attack across the whole of the area impacted by fire.

Members of the public are asked to remain vigilant for the potential for further damage to property and the fire remains uncontrolled. Trees affected by fire are a considerable risk and people are to remain clear at all times.

If members of the public are at immediate risk of being impacted by fire they are to ring 000 and request assistance.

- Check and follow your Bushfire Survival Plan. If your plan is to leave or you are not prepared, leave now.

- Only leave if the path is clear to a safe place.- Well prepared and actively defended homes can offer safety.

- You should not enter this area as the roads may not be safe.