CLEVELAND -- Safety remains a concern at the scene of a explosion and massive blaze at a Cleveland hazardous material plant.

Officials said the three-alarm fire started Thursday afternoon after an explosion in a tank at General Environmental Management, or GEM, on Transport Road off Rockefeller Road. The facility is located in an industrial area just west of downtown Cleveland.

GEM has been around for about five years, and is a storage facility for hazardous materials. It also processes industrial waste water.

Explosion Sparks Blaze At Hazmat Facility

Five workers were injured in the explosion and fire. They were taken to MetroHealth Medical Center, where they were treated for severe burns. Three people have been admitted to the hospital, and are listed in stable condition. Two people were treated and released.

Fire investigators are still trying to figure out what sparked the explosion, and what materials were fueling the massive blaze. The investigation could take several days.

Environmental experts from the Environmental Protection Agency and the Coast Guard are also on hand, making sure that the area is safe and also making sure there are no issues with the water used to douse the flames running off into the Cuyahoga River.

Fire crews also used foam to knock down the fire.

The blaze broke out at about 12:25 p.m., and smoke could be seen for miles.

GEM has been the target of numerous odor complaints recently near downtown Cleveland.

Air pollution inspectors traced a powerful and pungent odor to the company last month after receiving hundreds of complaints, WEWS reported.

The company agreed to address that odor problem.