COLUMBUS - Smoke billowed from the collapsed roof of a chemical warehouse late Tuesday afternoon almost 24 hours after the building went up in flames. “Columbus Chemical is on fire,” one 911 caller told a dispatcher. “There’s a bunch of chemicals in there. The whole roof is on fire.” Neighbors of the Columbus Chemical Industries campus feared workers were inside the building. “I want you to stay away,” the dispatcher told another caller. No one was inside, according to a plant spokesperson. The cause is still unknown and under investigation. A blast injured three firefighters who moved in to douse the flames. “The explosion happened at the time when they went into the building,” said Fall River volunteer EMT Jessica Dykstra. “They were thrown back with that explosion.” Authorities decided to let the flames burn out instead of risking additional injuries. Fire crews from several volunteer departments waited in standby mode in case the flames spread. “Within a minute, we heard our first explosion when we got there,” Fall River firefighter Chris Ackley told TODAY’S TMJ4 reporter Tom Murray. "Like a giant car bomb went off and then the debris." Police officers evacuated residents in a mile radius of the plant. About 140 homes were cleared. “I did what they told me to do,” said evacuee Sandy Zapotocny. “When I got down to the end of our street there, that’s when I saw a whole line of fire truck tankers waiting to come in to help put out the fire.” Several evacuated residents spent the night at the Columbus Super 8. It’s the only hotel in town. “I apologize to the evacuees and anyone else inconvenienced by the incident,” said Steve Quandt, Executive Vice President of Columbus Chemical Industries. Authorities allowed residents to return to their homes late Tuesday afternoon. The fire destroyed the warehouse that held more than a hundred chemicals in large barrels and small containers. Five other buildings at the N4335 Temkin Road campus are in tact. “Even with the worst chemicals that they use, anything in the air or that you would breathe would not be a hazard to human beings or animals at the level that is contained in the smoke,” said Dodge County Sheriff Todd Nehls. OSHA fined Columbus Chemical $4,324 in 2005 for eight serious violations, including a citation for mishandling flammable/combustible liquids.