A massive blaze at a plastics factory in Brisbane's north that released toxic smoke that spread across the city is being treated as suspicious, police say.
The fire broke out at a commercial plastics factory in Virginia at 3:30pm on Sunday, prompting police to declare an emergency situation and establish an exclusion zone on Pritchard Road.
Nearby businesses were evacuated by police, with concerns held for a nearby petrol station.
Police had warned residents to stay indoors and shut their windows due to the toxic smoke.
About four hours later, authorities said the fire at the Pritchard Road business had been brought under control and residents were advised they could "go about their normal business", after the toxic smoke abated.
The emergency situation was revoked late on Sunday night when the fire was put out, but fire crews remained at the site hosing down the area to prevent reignition.
Police have declared a crime scene and investigations into the cause of the blaze will continue this morning.
