It happened before midnight at a complex on Clay Avenue and Bond Street.
Firefighters say the blaze started in a storage room near a carport, destroying three vehicles.
The fire spread to an upstairs balcony, but fire crews were able to put it out quickly.
Two sets of power lines were damaged and fell to the ground. PG&E crews were called out for repairs.
Officials say firefighters had a tough time getting to the fire itself.
"We had to bring all of our lines and all of our resources from Clay and stretch them through the apartment complex to the alley where the fire was so that definitely hampered our abilities to get water on the fire," said Fresno Fire Battalion Chief Dan O'Meara.
Investigators are considering the fire suspicious because there were several other smaller fires in the area Monday night. An arson investigator is now working to determine the cause of the blaze.
The Red Cross is helping three adults and a child find a place to stay.
Officials say the fire department is on track to see more than 500 fires this month.