A derelict psychiatric hospital building has gone up in flames in Nelson.
Fire crews found the old Ngawhatu Hospital building in Stoke well-alight, when they were called by police at around 1am.
They've been there since, putting out the fire and dampening down.
Two fire trucks are still there.
Shift Manager Andrew Norris says the building is unoccupied and has no power, so the fire is being treated as suspicious.
Investigators will be visiting the scene today.