Just 12 minutes before it was slated to open for the holiday season, a propane tank explosion sparked a large fire at a Christmas market in downtown Vancouver Wednesday morning.

It happened inside one of the vendor stalls at the Vancouver Christmas Market, a large German-style outdoor holiday food and gift festival that was due to open for its very first day of business at 11 a.m.

Large flames and black billowing smoke could be seen shooting from the tops of tents in the outdoor plaza area in the 600-block of Hamilton Street.

A security guard at a neighbouring construction site told CTV News he heard a loud explosion moments before the fire.

There was concern that as many as 50 additional propane tanks in the immediate area are being used for heating the concession and vendor stalls.

Capt. Gabe Roder of the Vancouver Fire and Rescue Services said a contractor was drilling through a wall of a temporary hut when he unknowingly punched through the side of a 100-pound propane tank.

He said the leaked propane caught fire when it mixed with oxygen and found an ignition source, though that source is still unknown.

One person was injured while they ran from the fire. They were treated in hospital but their condition is currently unknown.

Four temporary vendor structures suffered damage, two of them extensively.

Roder said most of the heating for the temporary structures at the market is provided by portable propane tanks, something that was approved by the city and fire services.

Two adjacent streets were shut down and traffic was diverted as multiple fire rescue crews doused the fire with water. Vancouver Fire has launched a full investigation into the cause.

It is not known if anyone was in the plaza when the fire broke out.

The highly anticipated market, advertised as the ultimate European style holiday shopping experience, is set with rows of small wooden huts decorated in white lights and pine branches. It was expected to remain open until Dec. 24.

A festival spokesperson said organizers could re-open the festival by tomorrow morning.

Officials have ruled the fire was accidental.