He said a lot of smoke was generated from the fire, which spread through a large area of the unit and took about 45 minutes to be cleared.
"It was potentially quite a disruptive fire for the hospital unit. No one was hurt, the sprinklers had put the fire out."
Four fire engines from Tauranga and Greerton attended the fire and crews were there until just after midnight.
Bay of Plenty District Health Board Mental Health and Addiction Services business leader Eileen Hughes said there was fire damage to curtains and flooring in a one-bedroom unit and dampness to the flooring following the activation of the sprinkler system which extinguished the fire.
"All patients were briefly evacuated to another area of the unit during the event but have since been returned. The unit was closed for a short time last night but reopened soon after and is functioning as normal.
"One person was taken to ED with smoke inhalation but has since been discharged."