The rash of suspicious fires in Wellington County appears to be intensifying.

Just after 8 p.m. Thursday evening OPP and fire crews from Guelph - Eramosa responded to another suspicious structure fire.

The fire was reported on an historic property in Rockwood. Police said a structure on the property used as a pool house was engulfed in flames.

No one was in the building at the time and officials said there were no injuries reported.

Police said a witness reported seeing two men break the gate on the property and approximately 20 minutes later, they saw flames and called police.

Earlier Friday morning crews responded to four fires on three properties all within one hour.