LAKELAND, Fla. -- A CSX train hauling molten sulfur derailed early Monday, prompting officials to tell residents to close their windows and stay indoors for several hours.

A fire truck returning from a medical call around 1:50 a.m. Monday, Nov. 27, came across several rolled over and mangled train cars, according to the Polk County Fire Rescue. The crash became a hazmat situation when crews discovered the chemical.

The incident happened in the area of Kathleen and Strickland roads in Lakeland. Both roads remain closed as CSX staff work to clean the spill.

A further investigation discovered that nine rail cars were derailed in total and two of the rail cars leaked. Several thousand gallons of molten sulphur leaked from one car and cooking oil spilled from the other car.

CSX has not detected any impact on the surrounding environment so far.

The Federal Railroad Administration said Tuesday it now is investigating the incident.

According to the National Oceanic and Atmospheric Administration, molten sulfur is transported as a yellow or red liquid. It's handled at about 290 degrees to prevent it from solidifying.

If released, as apparent in the derailment, the sulfur quickly cools and solidifies. The chemical, when in contact with skin, is an irritant and smells like rotten eggs.

Photos: Molten sulfur spills in Lakeland train derailment

Kathleen Road is closed between Galloway and Spivey roads, and it's likely that stretch will remain closed until sometime Tuesday, officials say.

"They have to bring in some heavy cranes to start to lift some of the trains," Polk County fire spokesman Kevin Watler said. "It's a very slow process, it takes hours to do it."

Watch: Sky10 gets first daylight view of Lakeland train derailment

The train was traveling from Waycross, Georgia, to Winston, Florida, with three locomotives, 120 loaded railcars and 72 empty railcars, according to a CSX statement. Including the molten sulfur, it also was carrying cardboard, oats and rock.

Despite the crash, there are no reported injuries. It's not yet known what caused the derailment.

There are no evacuations currently in effect but as a precaution, people who live on Strickland Road were told to close their windows, turn off air conditioning and stay inside.

While allowed to open the windows and go outside, residents are asked to stay away from the derailment site.

CSX is still working to find out the cause of the derailment.

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