Heavy smoke billowed over Mobile, Alabama, on Wednesday afternoon after a "multi-story, oil rig-like structure" caught fire, according to Mobile Fire-Rescue. 

Several fire trucks and boats responded to the rig, which contains diesel, hydraulic fluid, oil, and other potentially hazardous materials. 

Mobile Fire-Rescue Chief Jeremy Lami told reporters at the scene that the fire was hundreds of feet in the air, complicating first responders' efforts. 

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"It can be challenging just because of the distance away from some of the hydrants and the fact that we're having to engage in some fire suppression operations that require the use of our aerial devices," Lami said at the scene. 

"Any equipment that we're using on top of that platform has to be taken up there with them, so we have to tote all that equipment up to the scene."

There were no initial reports of injuries. The fire appeared to break out in a shipyard on the east side of the Mobile River across from the city's business district. 

This is a breaking news story and may be updated.