"There's no doubt that [the officer] saved his life," Poulsen said. "If he didn't grab him out, he'd probably have been gone."
Poulsen said 911 calls started coming in about 6:45 p.m. Saturday to report a home at 3965 S. 2025 West in flames with a resident still trapped in the basement.
The victim's mother made it out unharmed, and when rescuers arrived she was screaming for her son to come out.
Christensen and another Roy police officer arrived just moments before fire crews. Christensen, who spent two years as a firefighter in Idaho before coming to Roy, ran in and disappeared into the smoke.
"The first thing [that hits you] is the smoke and the heat from the smoke and the flames," Christensen said. The only light in the house was the glow from the fire. "I yelled out to him and he wasn't responding to my voice."
Christensen soon reached the adult son, grabbed him in a bear hug and carried him out.
Minutes later as firefighters tried to battle the blaze, the whole top floor "exploded," Poulsen said. Everyone, including firefighters, managed to escape just in the nick of time.
"It was one of those that has the real true potential of being a deadly fire," Poulsen said.
Poulsen said the burned man, who he said was in his 40s, was possibly intoxicated and smoking in his basement bedroom at the time the fire started. Poulsen said investigators were returning to the home Sunday to try to determine the exact cause of the fire.
The home is a total loss.
Poulsen said firefighters never recommend anyone rush into a burning building because they could easily find themselves trapped as well.
Reporter Michael McFall contributed to this story.