A massive explosion at a food dye factory in Louisville, Kentucky on Tuesday left two people dead and a dozen others injured, as smoke billowed out of torn metal structures and rubble.

Two dead - one taken to hospital, the other found hours later dead in the rubble.Still no explosion cause.Air quality: No hazards found.All evacuations, shelter-in-places lifted.Sign up for our NewslettersTwo people have died following a large explosion in Louisville.

"When you're dealing with a large explosion like this, and such a massive amount of destruction, it's going to be difficult," one official said.