Three of the homes were considered fully destroyed, while two were heavily damaged, fire officials said.
Two firefighters and one civilian suffered minor injuries related to smoke inhalation and heat exhaustion, said Jeff Allen, a spokesman for the San Bernardino County Fire Department.
Allen described the fire as: "Very fast, very steep slope and it's very hot today. It's physically exhausting."
After the blaze, one couple was still missing their dog, who had helped alert them to the flames.
"She's the one that actually got us out of the fire," said Gustavo Nava. "She told us something was going on. We had no idea. Once we fled, she took off and we haven't found her since."
Nava and his girlfriend are hoping their golden Chihuahua, Penny, just ran away and was not harmed in the fire.
The blaze, later dubbed the Kendall Fire, was reported near W. Kendall Drive and N. F Street on the south side of Little Mountain, officials said.
The incident began as a half-acre vegetation fire until it rapidly grew to about 8 to 10 acres spreading up a hillside to homes on the ridgeline, according to San Bernardino County fire officials.
By 4 p.m. it was considered about 50 percent contained with flames no longer visible, but firefighters continuing to douse the smoldering ruins of the homes.
The neighborhood was under evacuation orders Saturday afternoon. Evacuation orders were issued for 20 homes off Skylark Drive, and an evacuation center was set in place at 3900 North Severance.
Multiple units with 120 firefighters responded to the scene that later grew to a third-alarm fire, county fire officials said.
SAN BERNARDINO: Kendall IC requesting 3rd ALARM, two structures involved. Multiple units enroute Krn— SB County Fire (@SBCOUNTYFIRE) July 2, 2016
The cause of the blaze was under investigation.