Shortly after 2:15 am in the early morning hours of Monday, a building fire was reported at 1848 S Main St, later changed to E Washington Blvd & S Main St.
Local video footage shows flames burning through a series of buildings, one of which was later reported to be a former clinic.
The fire was reported in a building which consisted of a series of connected structures. The Los Angeles Fire Department reported that the building once served as a medical clinic.
Crews arrived to find smoke filling the sky.
Firefighters requested power to the Blue line be shut down from Grand St Station and San Pedro St Station and requested additional units on the scene of the blaze.
Firefighters also requested police to the scene to assist with traffic control.
The building is a combined two-story and one-story commercial building.
Firefighters had to battle the blaze from an extended ladder, according to video footage on the Citizen app.
Firefighters also received a report of a water flow alarm in the area nearby. It is unclear if these two incidents are related.
Thirty minutes later, firefighters requested another additional unit to assist in the area. Heavy smoke continued to filter into the sky.
Firefighters reported they were making progress on gaining control of the fire about an hour later. They shifted their focus to hot spots throughout the building.
More than 100 Los Angeles firefighters battled to contain this fire over an hour.
No injuries have been reported.
The cause of the fire remains under investigation.