The evacuation of TVNZ headquarters in central Auckland has caused a delay in the 6pm 1 News programme.
Emergency services were called to the Victoria St office just before 5:30pm on Friday evening.
The road has been cordoned off between Hobson St and Nelson St.
Staff were seen huddling under umbrellas outside TVNZ offices for around 40 minutes.
At least eight fire trucks and a hazmat unit are in attendance.
Instead of the nightly news bulletin, TVNZ 1 aired an episode of Kiwi Living, with a notice informing viewers of the evacuation.
"Because of a fire alarm, we're evacuating our studios.
"We'll return to our scheduled programme as soon as possible."
1 News went to air 30 minutes behind schedule.
The cause of the evacuation is not yet known.