Calgary fire crews were called out to a southeast waste and recycling facility after a fire broke out in a pile of rubble.

Crews were called to ECCO Recycling & Energy Corporation in the Quarry Park business district in the city’s southeast at about  5:30 a.m. Monday for reports of a fire.

When crews arrived heavy smoke was coming from the structure and the building's sprinkler system had activated which stopped the fire from advancing.

Four employees were able to get out safely and two were assessed by AHS.

Firefighters extinguished the blaze and ventilated the facility to clear the smoke.

Officials say a large pile of waste materials consisting of wood, papers and plastics was the source of the fire and that damage to the facility is minor.

Fire crews used a Bobcat to move the debris around to put the fire out and remain on scene to monitor hot spots.

Calgary Fire Department Fire Investigators are looking into a cause.