Flames shot into the sky, eventually becoming a fiery explosion, outside the American Greetings building in Crocker Park Thursday morning.
Police and fire officials said two construction propane tanks caused the explosion, but the Ohio State Fire Marshal is investigating what started it.
No injuries have been reported.
People across the west side of Cleveland told newsnet5.com they could feel the ground shake when the tanks blew up.
People down the road said they could feel the heat from the fire.
Costantine Karadimas watched it happen, he said he saw the flames then ran for cover- he's glad he did.
"It was a loud boom, I was inside LA fitness and you could feel it, and there was smoke and fire...the shrapnel landed right where I had been standing seconds before," Karadimas said.
Buildings surrounding the area evacuated after the fire, many of them closed for much of Thursday.
newsnet5.com will bring you the latest updates on the Fire Marshal's investigation.