Caravan explodes in ball of flames by roadside

9NEWS Perth viewers have filmed an explosion on the side of the road as a caravan burst into flames. 

The incident occurred on Marmion Ave near the Eglinton turn off about 5pm yesterday.

Mobile phone video taken of the vehicle shows it consumed in flames on the side of the road before later exploding.

It is understood fire crews took half an hour to extinguish the blaze - but not before it gutted the caravan, causing $65,000 damage. 

The cause of the fire remains unknown.