Emergency services have rushed to the scene of an explosion in a Queenstown apartment complex early this afternoon. 

A witness told the Herald that all residents of the apartment where the blast occurred had escaped unharmed. 

"Everyone is out and safe," he said. 

But the apartment had suffered extensive damage, and was "fully involved" in fire. 

"It appears the explosion was caused by a gas bottle," a source said. 

Locals help emergency services at the scene of this afternoon's apartment explosion and fire in Queenstown. Photo / James Allan 

Police confirmed they were "assisting Fire Emergency in relation to a house fire on Ballarat St that occurred just before 12.30pm". 

"There are no reported blockages or injuries. Inquiries are ongoing as emergency services are still on scene."