A Fire and Emergency New Zealand (Fenz) spokesman said crews were called to the scene, at the intersection of McNulty Rd and Barry Ave, about 6.15pm after reports of a well-involved fire.
He said it was initially reported that people may have been trapped in the building.
"Our crews are currently just looking to clear the building because it's being treated as persons reported," he said.
"At the moment we're still working to do both of them and we're going from there."
In an update about 7.20pm Fenz said they had cleared the building, and the fire had been put out.
An Otago Daily Times reporter at the scene said it appeared the building had been extensively damaged.
Witness Greg White told the ODT there was "extensive smoke and flames" and he heard several bangs.
"Smoky in our offices across the road where I was working late."
He said it appeared to have spread quickly in the mezzanine floor of a newly set up tile shop.
Crews were still at the scene mid-evening.
Two Cromwell crews were first on the scene and were supported by two more fire trucks, one from Clyde, one from Alexandra, and a command unit from Alexandra as well.
