A motorist told the Herald police have stopped traffic in the area while firefighters battle the fire, which appears to be in the back of Crockers Property Management building.
At this stage, Cook said the fire is not threatening any neighbouring buildings, one of which is a BP station.
One Epsom local said they were made aware of the fire around 8.30pm after smelling smoke.
"It was very smokey, I smelt it first and I was inside," he said.
The witness believed the fire was a the Crockers Property Management building. He said traffic was becoming heavy on Manukau road and police were diverting motorists.
Firefighters are at the scene of a fire in Epsom. Photo / Matthew Vincent