The explosion sent a plume of smoke into the air at around 7:30 a.m. Wednesday at T.A.C. East Inc., which is located in the 2000-block of Gary Road.
"The plume of smoke could be seen approximately 2 miles. I live approximately 3 blocks away. When I got the call, I looked out the bedroom and could see the smoke this morning," said East Chicago Fire Chief Anthony Serna.
Chopper 7HD flew above the scene showing extensive damage to the building housing the business.
Fire officials said there were five people on site when the explosion happened in the garage area of the facility, near the boiler room.
Despite initial reports, the boilers appear intact. According to the fire department, the three men injured in the explosion were in the garage, preparing to clean one of the tanks. They were outside the tank at the time.
There are also four bays in the garage, so the explosion could have come from a different tank than the one that was being readied for cleaning, officials said.
The three workers suffered third-degree burns. Two of the men have been transported to Chicago hospitals due to the severity of the burns.
"We seen this big explosion and we heard it and we seen one guy running through the parking lot right there, flailing his arms like this and screaming," said witness Lamonte Smith.
T.A.C. East cleans out semi-trailers that haul different materials and chemicals. Fortunately, the fire did not cause any of the other nearby trailers, all of which are empty, to ignite.
"We're just very thankful that those employees were not injured any further than the burns they received," Fire Chief Serna said.
Serna said it could take up to two days to determine the exact cause of the explosion.