Washington State authorities are searching for a person of interest after an investigation into a Sunday house fire revealed that the two victims were fatally shot at close range before the blaze.

Peter Keller, 41, was named a person of interest and may be armed, police said. His wife, daughter and two pets were found shot dead inside their home after firefighters attempted to resuscitate the women, Q13 FOX reported. The wife and daughter’s names have not been released but the older woman was 41 and the younger 19.

Authorities had responded to the fire and discovered that the front door was barricaded and possible booby traps placed around the house. Police said filled gas cans were found throughout the house and they decided to send in a robot for their safety, the Valley Record reported.

Police say it appeared the two women were shot and killed, then barricaded inside the home as it burned. A dog and a cat were also found shot to dead.

"This is a crime of almost unbelievable evil," King County Sheriff Steve Strachan said Monday according to Q13 FOX.

Though they urge the public to contact them if they spot Keller, authorities recommend not approaching Keller since guns are missing from his home. He is described as 5-5, 175 pounds and considered an avid hiker.

"We have two victims who have been shot and killed, weapons are missing from the house, and we have not been able to contact Keller. We want to talk to him to see if he had any involvement in this case," Strachan told the Record. He told the paper that he was alarmed at the premeditation involved in the incident, considering the threat that the gas cans posed to responding firefighters.

“The shows how dangerous and heinous this crime was, “ he reportedly said.

Authorities found Keller's car abandoned in a public library parking lot Sunday night.

A sheriff spokeswoman told FoxNews.com that authorities have been in touch with Keller's immediate family, but would not go into details of the conversations.

"I’m just freaking shocked,” Sally French said. “I don’t know. I just don’t know. It’s just so hard to believe it’s real. Never was she afraid of her own husband. Never, never. She adored him. They just had an anniversary … they thought he was the most amazing man there was.”

Click here for more on this story from Q13 FOX.

Click here for more from The Valley Record.

Fox News' Edmund DeMarche contributed to this report.