Shortly before a fire gutted a newly built York Mills mansion on Thursday morning, a group of people could be seen running along the side of the house with gas cans, new video footage obtained by CP24 shows.

Toronto Fire responded to a blaze at the three-storey home on Dempsey Crescent, near Bayview Avenue and York Mills Road, shortly after 6 a.m.

Firefighters arrived to find the luxury home, which was listed for sale at $13.8 million, fully involved in flames.

The cause and origin of the blaze is under investigation.

Surveillance footage captured from an adjacent home sometime before the fire showed four individuals running along the side of the mansion. Members of the group were seen holding red gas cans and were dressed all in black. Moments later, the video shows a vehicle driving away from the property.

On Thursday evening, police confirmed an arson investigation is underway into the incident, releasing images of four suspects who allegedly set fire to the back of the home.

Police allege the four suspects used a dark-coloured Mercedes sedan to flee the area.

Two suspects are described as having a slim build, approximately five-foot-ten, weighing 125 and 135 pounds. The third suspect is believed to have a slim build, five-foot-eight, and weighs 125 to 135 pounds. Meanwhile, the fourth suspect has medium build, five-foot-ten and weighs 140 to 150 pounds.

Police said all four suspects were last seen wearing dark-coloured hoodies, face coverings, gloves, dark coloured pants and dark-coloured footwear.

No injuries were reported and it is not clear whether anyone is currently living at the home.

According to the listing, the mansion features a large underground six-car parking garage, a grand winding staircase, nanny suite, exercise room, spa and home cinema.

The owner of the home is a builder. He told CP24 that he has no idea why the property was targeted.