Train services have been halted and the public warned to stay indoors after a major factory fire in South Auckland.

Fire and Emergency NZ (Fenz) was called about 3.20pm on Friday to the large building fire on McGee St in Ōtāhuhu.

At 6pm Fenz said the fire was contained, and firefighters are dampening down hotspots.

There are still 15 firetrucks plus other support vehicles on the scene.

Train services between Ōtāhuhu and Middlemore were suspended because the fire was so close to the railway tracks.

The Ōtāhuhu factory fire as seen from Māngere Bridge. Photo / Jason Dorday

“An emergency mobile alert was issued shortly before 5pm to warn people in the area to stay inside with doors and windows shut, to avoid being exposed to smoke,” Fenz said in an update.

“Motorists should avoid the area and use any signposted diversions, so emergency services are not delayed in reaching the site.”