Two nearby fires could be arson

Two fires in country South Australia that started minutes apart, with one causing extensive damage to a house, may have been deliberately lit.

Fire crews were called to a grass fire on McIntosh Street at Nangwarry, north of Mount Gambier, just before midnight on Sunday.

About 10 minutes later a vacant house on Vaughan Terrace, less than a kilometre away, was also set alight.

Both blazes were extinguished and police are investigating the suspicious fires.