Miami-Dade Fire Rescue set up a 150-foot perimeter Thursday in a section of the Opa-Locka Executive Airport and began opening a 55-gallon drum marked "depleted" U-238 uranium that was found in the area.
WSVN-TV reports that the container was about 75% full of a product that indicated it was uranium. "There was a spill or leak in that work area," the Miami TV station says.
Officials say there have been no injuries related to the discovery of the container at the airport, which handles secondary traffic for Miami International Airport.
Fire teams are monitoring levels of radiation. A firefighter at the scene informs the fire dispatcher that the material is solid, not a liquid or dust, which will make it easier to block off a protective area.
NBC Miami describes the container as a 55-gallon drum found near a dismantled airplane in an area where old planes are taken apart.
The words "depleted uranium" are written on the container, according to the official at the scene.
The owner of the container could not be immediately established.
A preliminary assessment by some fire officials on the scene indicated they do not think the spill represents an environmental hazard, but that additional investigation will be necessary.
NBC Miami reports that the area is also the base of the U.S. coast Guard air and sea rescue station.