'Heard an explosion': Fears fire in Adelaide's south was deliberately lit

Detectives have been called in to investigate a suspicious fire that threatened homes in Onkaparinga Hills in Adelaide's south.

Security camera footage captured the alarming speed at which the fire consumed the scrubland yesterday.

The blaze started near Armata Road in Woodcroft shortly before 5pm before swiftly spreading across Education Road and threatening four homes and a horse stable. 

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Firefighters, aided by water bombers, successfully protected all the properties.

"It was definitely a scary experience for sure," local resident Shay Christo said.

"It's the closest I've ever seen it get to the house in probably 15 years of living here."

Authorities now believe the fire may have been deliberately lit, with CCTV footage capturing the sound of explosions.

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"We heard an explosion as well and saw a car take off," local resident Greg Ingleton said.

Four firefighters were injured while battling the blaze, and two koalas with burnt paws were also rescued during the operation.

This article was produced with the assistance of 9ExPress.