The effort continues to determine the exact cause of Wednesday morning's house fire in Petrolia.
Petrolia Fire Chief Lawrence Swift says the fire marshal's office believes the blaze was accidental.
"The determination so far is that it's looking like an accidental fire," says Swift. "We're waiting for forensic laboratory work to definitively decide what the cause of the fire was."
The female owner of the Queen St. home remains in serious condition in London hospital.
Damage is estimated at $120,000.
