Firefighters from around the city were last night working to extinguish a fire in a large farming shed in Green Island.
A witness said they heard three loud booms before a large commercial shed went up in flames in the afternoon.
A Fire and Emergency New Zealand spokesman said while the blaze was under control by 6.30pm, extinguishing it would take longer.

Crews were called to the blaze about 3.10pm, the first arriving about 3.20pm.
The fire was about 30m by 30m.

The Fenz spokesman said their strategy was to prevent the fire spreading and to protect any nearby buildings or structures.
‘‘We’ve got multiple crews at work with multiple hoses as well as some heavy machinery helping remove parts of the building so we can extinguish [the fire].’’