Firefighters remained at the scene of a devastating fire in Toronto's York Mills neighbourhood overnight, battling stubborn hot spots that could still be seen among the ruins of a gutted mansion.

The $2-million home was completely destroyed after it became engulfed by flames in a three-alarm blaze Tuesday evening.

Streets around the scene at Lauderdale Drive, located in the Bayview Avenue and York Mills Road area, remain closed to traffic as a result.

A police officer with 33 Division told CTV News Wednesday morning that the roof and second floor of the house had collapsed into the basement level. He said because of the damage, crews were unable to confirm earlier reports that a cache of weapons was found in the home.

Authorities are waiting for investigators with the Fire Marshal's Office to arrive.

The fire started sometime around 4:30 p.m. but by 11 p.m. the scene was still smouldering.

The FMO will determine if a plumber's mishap with a welding tool is to blame for sparking the blaze.

Firefighters faced a tough challenge at the scene as they were unable to go inside the home to put out the flames.

Crews were told that it was too dangerous to proceed inside after the first floor of the home collapsed at around 6 p.m. Instead, 70 firefighters attacked the flames from the outside of the home, using two ladder pumpers.

One firefighter suffered minor injuries after he slipped and fell on an icy patch of pavement. The roads had to be salted as below-freezing temperatures quickly froze the vast amounts water that were being poured on the scene.

There were no other injuries reported.

A woman who was inside the home babysitting two children safely escaped the fire with the kids in tow. 

The residents living inside the two neighbouring homes were asked to leave the premises and were sheltered inside a TTC bus as crews tried to prevent the fire from spreading. The adjacent homes suffered water damage.

According to real estate records, the Lauderdale Drive house sold for $2 million in 1998. The gutted mansion was being rented out to a family for $6,500 a month.