Firefighters got the call around 3:00 a.m. They say it took them about 20 minutes to put out the fire on Idora Avenue in Vallejo.
Three people lived in the home, two were home at the time. Firefighters say it started in a back bedroom but they haven't figured out what started it.
"There's nothing left of the room. I can't identify any objects except wire from a mattress. That's why we have investigators here to sift through everything to determine what the cause may have been," said firefighter Aaron Klauber.
The two people who were home were treated for smoke inhalation at the scene and then were released from care.
Firefighters say there were working smoke detectors in the home.
No firefighters were hurt in the fire. The Red Cross was brought in to help the displaced residents find shelter.
Three adults have been displaced in Vallejo because of a fire in this house. They are physically ok. Firefighters are looking for a cause. pic.twitter.com/lGJPss1Two— Amy Hollyfield (@amyhollyfield) January 1, 2019