Firefighters wore bulletproof vests to battle the intense flames. Prior to the blaze, there was some sort of conflict among six family members at the home in the 2100 block of Marter Avenue, police told Eyewitness News.
"Some of the information from the reporting party that came into dispatch was that one of the residents intentionally caused the fire, so there were approximately five other residents that were outside the residence," Simi Valley police Cmdr. Steve Short said.
"What our officers did is they started evacuating the residences in the general area and they started searching the area for who they believe might be responsible for the fire," Short said.
Soon after the fire started, Simi Valley police located one of the family members on the other side of the wall that divides the home from an adjacent residence.
Police said the man was injured and taken to a trauma center. The man is considered a "party of interest" in the arson investigation.
"He was strapped to a gurney. He was not free to move by himself. His legs were burned and he had a wound on his left shoulder," neighbor Gerardo Avila said.
Police at the location were seen pointing guns at the home and firefighters kept their distance while they tried to put out the blaze.
"There was a report that there were guns inside of the residence, and just a matter of security - what we do is (firefighters) deploy their bulletproof vests and (officers) offer them what's called 'force protection' just to make sure they can safely do their job and extinguish the fire," Short said.
Crews were able to keep the blaze contained to the home, which was destroyed.
Police said they've been called to the home before, but only for minor disturbances.
"It's a little bit concerning. It's a very quiet peaceful neighborhood," Avila said. "It's the first time we've ever seen anything like this."
Investigators don't know how the fire was started, only that it was intentionally set.