The blaze in the 10000 block of Vine Street erupted shortly before 10 a.m. in a large bucket containing a metallic substance -- believed to have been magnesium shavings -- and spread to cardboard, paper and other recyclables, said John Hisaw, division chief with the Lakeside Fire Protection District.
Worker at the business cleared out of the building, as did the occupants of a medical clinic and a dental office situated nearby.
It took 22 firefighters from the Lakeside department and its counterparts in El Cajon and Santee about 35 minutes to fully extinguish the flames. The personnel had to use a dry chemical retardant on the burning metal shards, since water will not put out that type of fire, Hisaw said.
The crew members moved much of the smoldering material out into an adjacent parking lot, where they were able to spread it out and douse it more effectively.
Damage to the building itself was limited to some charred sections of drywall, Hisaw said.
The cause of the fire remained under investigation this afternoon.