Late Tuesday morning, a fire marshal was still working to determine the cause of the blaze, which broke out at San Carlos Restaurant Supply at 929 Washington St. at about 12:35 a.m., said Stan Maupin, deputy fire chief for Redwood City and San Carlos.
The fire appeared to have started in a storage area where restaurant equipment was tightly packed on shelves and over most available floor space, Maupin said.
The fire was upgraded to three alarms at 1:55 a.m., Maupin said.
A neighboring 24 Hour Fitness gym had to be evacuated and remained closed late this morning.
Firefighters were able to bring the blaze under control by 2:15 a.m.
No one was injured, and no neighboring structures were damaged.
The fire did not appear to be suspicious, Maupin said.