A mid-day fire than consumed a business Wednesday in L.A.'s Industrial Eastside, sent three firefighters to the hospital, including one with critical burn injuries.   The Los Angeles Fire Department was summoned at 12:46 PM on September 19, 2018 to 2881 East Pico Boulevard in south Boyle Heights, where firefighters arrived quickly to find heavy smoke showing from an 80' x 100' one-story commercial building, housing a mercantile firm that was open for business with as many as a dozen workers on site.    Faced with an incipient fire and likelihood that occupants might remain trapped within the burning structure, the first arriving firefighters initiated an aggressive and well-coordinated offense with firefighting handlines from the front of the building, as the next arriving LAFD crew raised their truck's aerial ladder to allow four members to the roof to assess the possibility of vertically ventilating heat and smoke to allow their colleagues below in gaining access to the deep seated fire, and possibly rescue any persons remaining trapped within.   Less than ten minutes into the firefight, with fire showing from only one roof vent but heavy pressurized smoke in abundance, the four firefighters working together atop the structure suddenly became imperiled, when a section of the arched truss roof partially gave way, coming to rest upon contents, including tall storage racks below.    As flames erupted around them through the now highly precarious roof, the four firefighters scrambled for safety, including one who was forced to leap to a load bearing wall, where he clung precariously until being swiftly rescued by two of his four teammates. The fourth member of the vertical ventilation team was a probationary firefighter who had been upon the section of the roof that gave way. He quickly sought to self-extricate through heavy smoke and fire conditions by walking up the now steeply angled roof toward the southwest corner of the building, where despite severe burn injury, he held strongly to a parapet wall before being rescued by his fellow ventilation team members.   Three of the ventilation team members were taken to a nearby trauma center that co-houses a burn center for further assessment and treatment. One of the three was determined to be uninjured, while another was provided initial hospital care for 2nd degree burns to his hands before being released to outpatient care. The probationary firefighter, who rode down on the burning roof was the most seriously injured of the three. Initially described as in critical condition, his status was upgraded to serious but stable condition on hospital assessment, where he remains in specialized care for 2nd and 3rd degree burns to multiple areas of his body.       Despite the challenge of structural collapse, multiple injured colleagues and downed high-voltage power lines, one hundred-fifty LAFD firefighters confined the intense fire to the structure of origin, fully extinguishing flames in just two hours.    Fire loss to Passion Imports, a purveyor of apparel, accessories and souvenirs, is still being tabulated. Los Angeles Fire Department responders were successful in preventing civilian injury or allowing any fire spread to a pair of nearby buildings, including a fully adjoining building to the west. The cause of the major emergency fire remains under active investigation.    Dispatched LAFD Units: E17  RA17  RA25  E202  T2  E9  E209  E221  T21  BC1  BC2  SQ21  E14  E21  T9  E203  T3  CM22  E220  T20  EM11  BC11  E3  UR3  HR3  RA3  UR88  BC14  E25  E201  T1  E4  E10  E250  T50  RA14  RA21  EM13  EM5  EM25  CM21  EM18  BC13  RM4  AR1  AR10  E15  T11  E233  T33  E64  BC18  BC9  BC10  AR21  AR12  BC14  EA1  EM4  EM9  RA26  RA47  HU59  HL7  CM41  AR19  AR37  T94  E294  E40  T93  E293  E49  E69  T61  E261  T12  E212  E62  T3  E203  E3  T3  E203  PH1  BC1  T27  E227  T95  E295  EM1   Incident Photo Gallery