City Fire inspectors are not ruling out arson as the cause of last night's house fire on Marks Street. Bob Vander Ploeg looked over the site this morning and says he's handing it over to the Ontario Fire Marshall. He says it's because they cannot totally rule out that the blaze was deliberately set. Vander Ploeg says it was fortunate that a neighbour was able alert the occupants of the house in time to escape the fire.