The cause of Thursday's fire that roared through the second storey of a 1940s-vintage home in Porter Creek remains unknown today, though Whitehorse RCMP are looking for three young people.

There is an eyewitness account of three teenagers, two males and one female, leaving the vacant building on Centennial Street shortly before the fire broke out.

'These individuals are persons of interest to police,' Cpl. Grant MacDonald said in a press release issued this morning.

MacDonald is asking anyone who may have noticed any people in the area or suspicious activity to contact the Whitehorse detachment at 667-5555, or call Crimestoppers at 1-800-222-8477.

Whitehorse fire chief Clive Sparks said a suspicious blaze could be accidental, a result of mischief, or arson, though arson carries very specific definitions, such as having been lit for personal gain or revenge.

The white wooden building, with the basement and main floor still largely intact today, was covered by liability insurance, but not fire insurance.

For the first hour or so, firefighters faced an intense blaze.

With the outside walls protecting the heart of the beast, flames persisted despite enormous amounts of water pouring into the building from several hose lines around the perimeter, along with the water cannon mounted on the new ladder truck.

Attempting to get inside for an interior attack was out of the question, Sparks said while commanding operations.

'It would be very easy for the ceilings, the roof and the floors to collapse on us,' he said. 'The upper floor appeared to be fully involved when I arrived here.'

Not until flames burst through roof were firefighters able to collapse the intensity of the fire, primarily with the use of the new cannon pumping out somewhere around 650 to 700 gallons per minute.

Even still, it wasn't until the city-owned excavator ripped into the second-storey walls and roof cavity that the last pockets of heat and flames were exposed.

There were a dozen or so firefighters in all, including the regular shift and other staff who were called in to help operate the ladder truck and two regular pumpers, along with the emergency command vehicle.

City utility staff were on the scene to assure Sparks his water supply was secure, with the Porter Creek reservoir still showing 98-per-cent full.

Staff from Yukon Electrical Co. Ltd. shut down power to that section of Centennial at 1:05 p.m., affecting about 12 homes until the line was re-energized at 3:55 p.m.

RCMP officers were parked on the Alaska Highway with lights flashing to slow down drivers, as many passersby had pulled over to watch.

Numerous residents of Centennial stood along the street and watched, as did others from around the city who'd caught wind of the blaze.

Cary Goodman watched from his rooftop next door, only about six metres away from the burning building.

Called by a neighbour, Goodman hurried home from his Quartz Road business and placed his own water hose on his roof to keep it cool.

'Thank God for the fire department; that's all I can say,' Goodman said. 'And good thing for the south wind.'

While Goodman's home a stone's throw away on the south side, to the north of the building in the direction the wind was blowing is a vacant lot.

As firefighters battled the swirling flames bursting through the rooftop, Marilyn and Robby King, owners of the house, watched from a distance.

'It has been here forever,' King recalled in an interview after the fire had been defeated and the backhoe continued digging into the walls and roof. 'I used to get babysat in that house a long time ago. The Slonski girls use to babysit us.'

King said he and his wife purchased the property from the Slonski family last year, with an aim to restore the structure that has been vacant for several years, and was without heat or power.

'There is a lot of history in that building.'

King said it had already been inspected by an engineer who was unable to provide a final recommendation until more of the interior drywall was removed so he could assess the structural condition of the building.

'I would still like to save it, and I think there is some good value there with what is left,' he said.

He pointed out he had asked the fire department and hoe operator to do what they could to leave the main floor structure intact.

It's a solid building made of fir, King emphasized. The floor on the second storey, which supported hundreds if not thousands of gallons of water that came cascading out when the wall was opened up, is made of two-inch, tongue-and-groove fir boards, he noted.

He said the basement floor remains intact, as does the second floor but for a small section.

At 2,100 square feet per floor, it gets expensive to go in and rip everything down and start rebuilding from scratch, King said.

In the end, he admitted, there may be no choice.

King said he was told eyewitnesses had seen three individuals fleeing the area shortly before the blaze broke out.

Having kids break into the building has been a problem both recently and over the years, he said.

Sparks, meanwhile, said he has concluded from the evidence available that the fire started outside the building on the back porch area facing the Alaska Highway.

Because the building and the busted-up dÈbris remain unstable, investigators are not able to go inside the building to inspect the interior, Sparks explained.

All evidence indicates, however, that the fire started outside on the ground floor and quickly raced into the second storey, with minimal damage to the main floor.

Sparks said it appears there was only one room on the main floor with any degree of heavy damage, as there is still paint on the walls in the other main-floor rooms.

It is a credit to fire crews that they could go in and halt the spread of an intense blaze in such a structure, while saving a good portion of the building, he said.

'I am quite pleased with the outcome, and the equipment, and with what the crew did,' Sparks said. 'In fact, I am more than quite pleased, I am very pleased.

'One of the biggest things that came out of this was it proved the value of the new ladder truck, and what it is capable of.'

Sparks said with no fire insurance to work from, and the age of the building, it's difficult to estimate the value of the loss. But he suspects that replacing the third storey on the building could run in the $500,000-range.

Lloyd Ryder, who grew up in Whitehorse, recalls the building being used in 1942 by crews involved with the construction of the Alaska Highway.

But it was built in the early '40s by the Pan Alaska Airway company on the east side of the runway to serve as quarters for pilots and other staff, he said.

Ryder said he believes it was moved to Porter Creek in the 1950s by Harry and Pete Versluice.