Firefighters are trying to figure out what sparked a mobile home fire that killed a Rhea County man on Saturday. They said the call came in around 10 a.m. for a home on Dyer Hollow Road in Dayton.

Family and friends told Channel 3 that 52-year-old Ronnie Sullivan is the man firefighters found dead inside the home.

"It's hard to seem real, really. I mean he was always pretty careful. He was a good guy. He was always nice to everybody. I just hate to see that happen to him, you know?," Justin Houston, a friend said.

Friends of Sullivan's are struggling to understand how this happened. By the time firefighters arrived to the mobile home, it was too late.

"It's sad. It's really sad. I hate to see that happen to anybody, but he was a really quiet guy," Heather Johnson, a neighbor said.

Johnson lives next door and said she didn't notice anything out of the ordinary when she left for work on Saturday, but that soon changed with a phone call.

"It was fine. There was nothing going on right here. Nothing at all and then my husband called me about noon and said that the fire department and everything was over here," Johnson said.

Johnson met Sullivan right after she moved in next door with her family about a week ago. She described him being quiet and nice.

Firefighters said he lived alone at the mobile home. Right now, they aren't sure what caused the fire.

"I hate it that he was by hisself. I mean anybody being by their self especially older people. I hate to see that," Johnson said.

Friends said they're in shock about the damage the fire caused and Sullivan's death.

"Til it really hits right there close to home, you never really think about it. It's hard to think it's that quick. Everything is gone," Houston said.

Firefighters aren't suspecting any foul play. An autopsy will determine the cause of death for the man.

Other agencies including the Rhea County Sheriff’s Office, the TBI, and the Tennessee Bomb and Arson division were also investigating the fire. 

Stay with Channel 3 as this story develops.