The children were 1, 3 and 4 years old, and the 24-year-old woman who was looking after the children was overcome by smoke while on the phone with a Nye County emergency dispatcher, Sheriff Tony DeMeo said.
The intensity of the fire in Pahrump, about 60 miles west of Las Vegas, initially turned rescuers back, he said.
Thick black smoke poured from the windows and doorways as firefighters entered the home, Pahrump Fire Chief Scott Lewis said. A deputy pulled one of the children from a window and administered first aid, and one firefighter sustained non-life threatening burns along his neck as he carried two children from the house, he said.
Another adult in the single-story, single-family manufactured home was injured, Lewis said. It took roughly 20 firefighters 40 minutes to snuff out the flames, he said.
An off-duty sheriff's deputy and two on-duty deputies also sustained nonlife-threatening injuries, DeMeo said.
The dispatcher who spoke with the babysitter was placed on emergency leave, and DeMeo said fire investigators planned to review the recording of the call. The recording was not immediately made public.
DeMeo said the state fire marshal was investigating the cause of the fire.
Jennie Wheeler, the woman who was listed as the owner of the house along with Charles Rodney Wheeler, declined to speak with a reporter.
"I can't talk about this - I'm too distraught," she said. "I really can't talk."
Associated Press writer Ken Ritter in Las Vegas contributed to this report.