Strike Force Vulcan officers are hunting an arsonist responsible for two separate fires in Rockingham and Waikiki on Wednesday.
A fire was a reported around 4:35pm in a park surrounded by Santa Monica Drive, Bolsabay Drive, Ennis Avenue and Buttermere Approach in Waikiki.
The second fire was reported around 6:15pm and Emergency Services were called to a fire in bushland near the corner of Simpson Avenue and Louise Street in Rockingham.
Around 20 metres of bushland was burnt.
The fires are considered to be suspicious.
Anyone with information is asked to call Crime Stoppers on 1800 333 000 or make a report online at crimestopperswa.com.au.
A reward of up to $50,000 is available for information that leads to the identification of the arsonist and conviction.