Police have taken over the investigation into a fire at Old City Hall on Monday night after investigators determined that it was deliberately set.

Toronto Fire Chief Matthew Pegg told CP24 on Tuesday morning that investigators with the Ontario Fire Marshal and Toronto Fire Services made the ruling after wrapping up an extensive investigation at the historic building at around 4:30 a.m.

“I can confirm that the fire was intentionally set. It is now in the hands of the detectives at Toronto police,” he said.

The one-alarm blaze broke out in the southeast corner of Old City Hall at around 8 p.m.

Detectives said Tuesday afternoon that the suspect in the arson set “three separate fires” inside the building before fleeing the scene.

Toronto Police Association President Mike McCormack said that it took police officers two hours to get to the Old City Hall because they were tied up with other calls.

“We are seeing this across the city in every division where the response times are being impacted by the lack of staffing and that is something we have been very concerned about,” McCormack told CP24. “The reality of policing in Toronto is that we don’t have the personnel that we needed.”

Pegg said that crews first became aware of the fire after the building’s sprinkler system went off.

He said that the damage from the blaze is estimated at about $100,000, which he called “extraordinarily low” given the circumstances.

“We are very fortunate that that this building has sprinklers and that the system worked as designed. It would have been a much different scenario had that not been the case,” he said. “We had three sprinkler heads activate last night. The sprinkler system controls the growth, development and spread of the fire so in essence it keeps it in check until our firefighters arrive and can suppress the fire.”

Pegg said that there is smoke and water damage from the fire but no structural damage.

According to a spokesperson from the Ministry of the Attorney General, the fire impacted the Provincial Offences Act appeals office but did not damage any paperwork related to criminal cases.

“The Provincial Offences Act appeals office and matters scheduled in one courtroom have been moved within the building. The courts remain operational at this time,” Brian Gray said.

On Tuesday afternoon, detectives released a surveillance camera image of a middle-aged white male sought in relation to the investigation.

He was seen wearing a navy and red jacket, a backpack, olive drab shorts and flip flop sandals.

Toronto Fire Deputy Chief Larry Cocco said that the fires were all confined to a main office used by the Ministry of Attorney General’s restitution, fines and appeals office.

He said each fire scene consisted of little more than some “combustible papers” that were set alight, adding “there was nothing complicated about this arson.”

Cocco also dismissed a report that the suspected arsonist was still nearby or inside the building when fire crews arrived.

“Our information indicates that there was no one present.”