McDonald's in Ramona
The McDonald’s Restaurant in Ramona. Courtesy Cal Fire

A fire that erupted inside a fast-food restaurant in eastern San Diego County shortly before sunrise Wednesday caused extensive damage to the business before firefighters were able to subdue the flames.

The non-injury blaze began spreading through a basement storage area at the McDonald’s in the 1500 block of Main Street in Ramona at about 5:45 a.m., according to Cal Fire.

Employees inside the building when the fire broke out were able to safely evacuate, said Frank LoCoco, a captain with the state fire agency. No customers were present at the time, he said.

It took Cal Fire crews and firefighting personnel from the cities of Poway, San Diego and Santee about 35 minutes to gain control of the blaze, LoCoco said.

The cause of the fire remained under investigation Wednesday afternoon, though preliminary indications were that an electrical problem of some sort may have sparked it, according to LoCoco.