Arson squad detectives are investigating an explosion which damaged four automatic teller machines at Harbourtown last night.
The explosion appears to have been timed to coincide with Australia Day fireworks nearby in the city.
No one was injured.
Police were called about 8.15pm with a report of an explosion in the vicinity of the Harbour Town Shopping Centre in West Perth.
A police spokesman said an assessment of the area suggested two ATMs were targeted by the thieves but four were damaged in the explosion.
"There is some structural damage to the building and this will require further assessment before it is deemed safe," the police spokesman said.
Detectives are asking anyone with information regarding this incident to call Crime Stoppers on 1800 333 000.
Callers can remain anonymous.