On Wednesday night, the Prince George’s Fire Department called in additional resources to assist with the effort, including brush and foam units.
They used equipment from BWI and the Naval District of Washington that could spray fire retardant and move at the same time.
Thursday morning, crews attacked the pile with bulldozers to spread out the burning mulch, then soak it with water and smother with dirt.
The fire was said to be contained to an isolated area and no surrounding structures were ever in any danger.
Crews used the water supply from a nearby school to snuff out the flames.
Officials don’t yet know what caused the blaze.