SPOKANE VALLEY, Wash. -

Police and fire investigators are asking for the public's help as they investigate a Spokane Valley fire at the home of a couple who are missing under suspicious circumstances.

Late Friday afternoon, authorities confirmed a vehicle matching the description owned by the homeowners was found in rural Benewah County with two bodies inside. The identification of the couple found in the vehicle will be done after the coroner performs an autopsy to determine their cause of death.

Thursday night firefighters responded to a house fire in the 1500 block of South Bettman Road after neighbors reported hearing an explosion just before 4 p.m.

“When they looked over this way they saw what they described as dust settling after they kind of looked at it a little bit longer trying to figure out what happened they saw smoke,” Assistant Fire Marshall Bill Clifford said.

It didn't take long for investigators to determine the fire was started intentionally and the homeowners – John Tiffany, 76, and his wife Sandy, 68 – are nowhere to be found. Neighbors told investigators they mostly kept to themselves and that certainly doesn't make this any easier.

“Where they are at, we want to find them we have questions for them, we want to make sure they're safe," Clifford said.

An arson dog was able to sniff out gas or some other type of liquid accelerant that was used to start this fire. It only took firefighters four minutes to get on scene and get the fire under control. From the outside of the residence you can't really see a lot damage but the interior is unlivable.

“The house, all of that can be replaced. Somebody's life ... we want to make sure that they are going to be safe, we don't know where they are at, we don't know if they are still in their car or if they are on vacation. You know we don't have any of that information so anybody that has information of their whereabouts we sure would like to talk to them," Clifford said.

Neighbors say the Tiffanys drove a white KIA SUV and may have had a motor home in the driveway as well. No one could be sure when they last saw either vehicle.

“Our biggest concern is the safety and welfare of these homeowners and finding out where they are at,” Clifford said.

Investigators said that two relatives stopped by the residence and are working to find a current picture of the couple. Those family members aren't exactly sure when they last spoke to the couple but it was somewhat recently.

If you or anyone you know has information on their whereabouts or the fire at their home you're asked to call the Spokane Valley Fire Department at 509-928-1700.