A fire burned through a commercial building in South Los Angeles, sending flames into the night sky on Monday, April 3. Firefighters declared a knockdown after three hours, according to a report.The fire ran through duct work at a food-processing plant, and firefighters had to battle flames from outside the building, according to the report. An “active gas leak” contributed to fueling the flames.The LAFD Arson Unit is investigating the cause of the fire.