Local firefighters were kept busy overnight after five fires were lit in the Kwinana area.
The first started around 8.30pm on Christmas Avenue in Orelia, followed by three on Gilmore Avenue, Medina Avenue and Seabrook Way in Medina and one along Sulphur Road in Kwinana.
The last fire was reported around 10pm.
A Department of Fire and Emergency Services spokesperson said they believe all the fires were deliberately lit.
Anyone who saw any suspicious activity at the time and locations of the fires is urged to contact Crime Stoppers on 1800 333 000.
Teen accused of ordering firebomb attack on Baldivis tobacco shop
City of Mandurah sees sharp rise in animal cruelty reports
Geoff Valentine returns to Peel Thunder as senior coach
Golden Bay woman charged with lacing colleague's curry lunch with snail poison
Cooloongup man charged over alleged sexualised online conversations with a child
Bushfire readiness takes centre stage at City of Kwinana's free Summer Sounds festival
WA Open Golf Championship to tee off at Secret Harbour Golf Links
Halls Head named WA's most persistent storm damage hotspot
Four illegal e-bikes to be crushed after police crackdown in Halls Head, Falcon