About 40 firefighters are dealing with the aftermath of an ammonia leak in South Auckland.
The leak, inside a commercial building in Manukau, was reported on Tuesday afternoon. Initial reports suggested that one person was trapped inside.
The Fire Service says staff reported headaches, and neighbours complained of a smell.
Police were called to evacuate properties within a 500-metre, downwind stretch of the property once an overturned 1000-litre tank was found.
Crews in chemical suits are washing away residue from the ammonia.
One person was taken to hospital suffering from ammonia fumes.