Fire crews are on the scene of a chemical spill at a water treatment plant at Joyner in Brisbane's north.
Nearby residents are being warned about gas leaking from the spill site.
They have been told to stay inside and close their windows and doors, especially if they live to the east of the facility.
It's not yet known what caused the leak but fire and emergency services are performing atmospheric tests.
A Public Safety Preservation Act declaration has been made to establish a 250-metre buffer zone around the plant.
People are being told to monitor conditions and follow the advice of emergency services.
Authorities say the leak, which began earlier Sunday afternoon, is likely to take some time to deal with.