The spokesman said that although firefighters arrived at the scene within three minutes of the report being received, the house was already engulfed in flames.

"The bodies of an elderly woman and two men, who died of carbon monoxide poisoning, were found inside," the source said. "Two other residents were rescued."

Investigators believe arson is the most likely cause of the fatal blaze.

A failed attempt to set the house on fire was prevented late on Tuesday. A day earlier unidentified arsonists set on fire a garage belonging to the owners of the house.