Fire crews were called to the blaze at about 9:15 p.m.
The homeowners said they heard a popping noise they thought was hail but when they checked, they found flames at the back of their home.
The Lehi Fire Department said the flames traveled up the side of the house and burned in the attic for a while before homeowners noticed.
The smoke detectors did not go off because there was no smoke in the house.
A neighbor said their daughter called 911 after the homeowners pounded on their door for help.
"We got everyone out, we grabbed their kids we took them inside to the other neighbors house," the neighbor said. "A lot of people brought them stuffed animals, blankets, just made sure their kids were OK. Talked to the neighbors, they were in shock but calm and just consoled them. Made sure we were safe and out of the way."
No other homes in the area were damaged.
Crews said the home is a total loss.