A Horseshoe Bay homeowner who stepped out to buy milk Thursday afternoon returned to find his house on fire.
The fire started on the deck of the duplex and was discovered by West Vancouver police - who arrived at the home as the same time as the owner.
The officers were responding to an intruder alarm that had been triggered at the residence, said Martin Ernst, assistant fire chief for West Vancouver Fire and Rescue.
The house was "locked up tight," according to Ernst, and there was no sign of a break-in.
The fire spread to the inside of the house and also broke through the firewall to the other side of the duplex, whose owners were away on vacation.
Crews were kept busy for around an hour before the fire was out.
The blaze caused "minimal fire and some smoke damage" to both homes, according to a release.
Investigators are still searching for the cause of the fire.