EL CAJON, Calif.—A predawn fire gutted a commercial building in a strip mall near Interstate 8 and State Route 67 on Jan. 5, causing an estimated $2 million worth of damage, authorities said. The non-injury blaze in the 400 block of Broadway in El Cajon broke out for unknown reasons at about 3 a.m., Heartland Fire & Rescue spokesman Andy McKellar said. Due to the intensity of the flames, firefighters had to remain outside the building while battling the inferno, which eventually led to a major roof collapse, McKellar said. It took crews from six San Diego-area emergency services agencies about two hours to fully subdue the fire. The blaze left the structure—which had housed a restaurant, a barbershop, and a smoke shop—a complete loss, McKellar said. Crews were expected to remain at the scene into the evening. “It’s still smoldering,” the spokesman said in the early afternoon. “It’s too hot to clear the debris [yet].” The cause …