A grisly discovery was made by a homeowner in the 6000 block of West 1st. Ave in Kennewick Thursday late afternoon.

According to Kennewick Police, a man had been living in a van which was parked near a home on that road, he lived with a Labrador dog.  He'd been there for a number of months, but the homeowner found both of them dead inside the vehicle.

According to some news reports, the man was homeless, which is why he was living in the van, likely parked there with permission from the homeowner.

Authorities say upon investigation the man and dog died from carbon monoxide poisoning. The windows were all rolled up on the vehicle, it's possible they passed away during the nighttime hours while sleeping.

The man apparently used a propane heater to provide warmth and cook food. He was using a parabolic heater, which looks somewhat like a circular fan. It uses a 'disc' shape to spread it's heat further.

Authorities say the unit gave off enough carbon monoxide to kill the man and dog, likely in their sleep.

Officials warn against using propane heating devices indoors, or in enclosed areas without ventilation, as the fumes can build up and harm you. Carbon monoxide is odor and colorless, so you won't know you've been poisoned, possibly, until it's too late and you pass out.