NIAGARA FALLS, Ont. - Niagara regional police say a house fire that was spotted by a U.S. Coast Guard patrol boat last week is a case of arson.

Police say the fire in the city of Niagara Falls, Ont., was at a vacant home that was destroyed in the overnight blaze.

U.S. border agents discovered the fire shortly after 1 a.m. last Thursday and, after not seeing any initial signs of fire or rescue vehicles, set off their sirens and shone spotlights to alert residents.

An initial report said the patrol agents led a family of four out of the burning home but Niagara police say neighbouring homes were the ones evacuated while the home on fire was found to be unoccupied.

Niagara police say the home was under construction at the time of the incident.

They say the Ontario Fire Marshall has ruled the fire to be a case of arson.

Anyone who may have been in the area or who may have knowledge of the incident is being asked to contact Niagara police.