A car driven into a Fyshwick warehouse early Tuesday morning burst into flames and caused extensive damage to a number of businesses in the building.
Detective Superintendent Ben Cartwright said police had "no idea" why the building was targeted but said the fire was being treated as suspicious.
"At this stage the inquiry is in its initial stages, but at this point it seems to be that someone has driven the car into the premises between 151 and 155 Gladstone Street and a fire has resulted at the time or shortly thereafter," he said.
"We are following all lines of inquiry to get to the bottom of that and the reasons that this business may have been targeted."
The incident happened about 3.20am. Anyone who saw anything suspicious is asked to Crime Stoppers on 1800 333 000 quoting reference number 6023050.