Riverside County fire officials said the blaze occurred inside the Rancho California Inn on the 41000 block of Moreno Road at about 12:35 a.m.
It took nearly 60 firefighters more than an hour to put out the multiple-alarm blaze.
No injuries were reported, but six people were displaced by the fire and were assisted by the American Red Cross.
The cause of the fire was under investigation.
City News Service contributed to this report.