Fire and Emergency crews were called to an electrical fire at Affco in Whanganui on Wednesday.
Four fire engines attended just before 3.30pm.
Whanganui station officer Shane Dudley said they had to wait for Powerco to turn off power at the plant before sending any of their crew inside.
He said the fire alarm was called early on and set off evacuation sirens which enabled all staff to get outside to a safe area.
"The fire is out, the power's been isolated and the plant engineers are currently in there getting some life back into the plant."
Dudley confirmed no one was injured.