KCRA-TV reports that the fire started at about 4 a.m. Sunday on the second floor of the Pizza Factory on Main Street.
Highway 70 was closed and power was shut off, but restored, as the Quincy Fire Department fought the blaze.
Firefighters tell the television station that apartments above the pizza place sustained smoke and water damage.
Arson investigators are trying to figure out the cause of the fire.
Quincy is about 80 miles from Reno, Nev.
Information from: KCRA-TV.