Yellowknife (Feb 04/05) - A spectacular fire that destroyed a government warehouse in Old Town two weeks ago was caused by a propane leak, fire investigators have determined.

The highly volatile gas gradually filled the metal-sided Department of Fisheries and Oceans (DFO) warehouse on Jan. 17 before being ignited by a spark from an electric motor, said Yellowknife deputy fire chief Darcy Hernblad.

The resulting explosion rocked homes across the street and destroyed a large part of the building, used by DFO officers to store boat motors, solvents and nearly 20,000 rounds of ammunition.

"We are thankful nobody was hurt," Hernblad said. "Anyone in the building would probably have died."

Members of the Yellowknife fire department and a federal investigator from Ottawa determined the propane leak came from a cracked pipe, Hernblad said.

"It is not suspicious at all. It was an accident."

Firefighters had trouble fighting the blaze, in part because the metal-sided warehouse acted "like an oven," Hernblad said.

The 26 members of the Yellowknife fire department who battled the blaze also had to contend with 20,000 rounds of exploding ammunition.

"Without a doubt, it was dangerous," Hernblad said.

While propane leaks are fairly common, he said, "99 per cent of the time" the flow is stemmed before it results in an explosion.

He advised people to check their propane lines and take care when hooking up appliances that use the gas.

A DFO official estimated last week that the fire caused several hundred thousand dollars in damage. It could be several months before the equipment lost in the blaze - including three trucks parked outside of the warehouse - are replaced.