Dispatchers received a 911 call from the man around 10:30 p.m. reporting he had wounded his roommate, said Capt. Nick Almquist with Snoqualmie Police.
When officers and medics arrived at the home in the 45000 block of North Bend Way, they found the body of the shooter's roommate. Almquist originally said the victim was the brother of the shooter, but later confirmed they were long-time friends and roommates.
Almquist says their investigation is still ongoing, but it appears to be an accident.
"He was showing his firearm to his (roommate) and he was checking to see if it was loaded and it went off," Almquist said.
The suspected shooter was arrested and booked into the King County Jail for investigation of manslaughter.
"Whenever somebody is killed and there is some sort of negligence involved it fits the category of manslaughter," Almquist said. "Even though it was a horrific scenario, we do have to follow through with filing the case with the King County prosecutor's office."
Almquist said the two had been drinking a small amount of alcohol before the shooting but "nothing that was substantial, whatsoever."
The victim's name has not been released. Almquist would only say both men were in their 40s.