The Ontario Fire Marshal has determined a major fire that involved three homes on Thornhill Place in Waterloo last Thursday was deliberately set.

Waterloo Region Police Staff Sgt. Ken Jessop says “Late yesterday afternoon they determined that the fire is deemed arson and at that point in time we’ll take over the investigation, still working with the Ontario Fire Marshal.”

A criminal investigation is now underway to try to locate whoever is responsible for starting the fire, which destroyed two homes and damaged a third.

Detectives are hoping new information will help lead them to the suspect(s).

Police say they have received calls about suspicious activity in the area, but are asking anyone with information to contact them.

“We’ve actually received some tips from the public, however we’re interested in receiving more,” Jessop says.

Fire crews were called to the scene early Thursday morning and one family had to be evacuated but no one was injured.

Repairs have begun on the least damaged home, where a family was already living.

Jessop says “We are looking at the two houses that were under construction and that appears to be…determined where the fires originated from.”

There is still no word on exactly where or how the fire was set.

The estimate of cost of the damage has also been increased to $850,000.