Three people had to be taken to the hospital for smoke inhalation including a grandmother and grandfather, who also suffered burns to his face.
Several months ago other units nearby were destroyed by a fire that forced several families to relocate.
Fire officials say this latest blaze shows just how important it is to check your fire alarms and extinguishers.
"And if you can establish a home evacuation plan with your family because if this fire would have happened overnight and nobody would have noticed the fire it could have advanced and perhaps killed somebody," Tony Escobido Fresno Fire Department.
Red Cross volunteers showed up to help the affected families but we learned most are staying with family or friends until they get back on their feet.
The cause of the fire is still under investigation.