CARLSBAD, N.M. — Emergency crews battled a fire Wednesday at the southeastern New Mexico site where the federal government seals away its low-grade nuclear waste, including plutonium-contaminated clothing and tools.

Several people were taken to the hospital after a truck hauling salt caught fire about 11 a.m. Wednesday at the Waste Isolation Pilot Plant near Carlsbad, N.M.

All employees have been evacuated and none of the radioactive waste has been impacted, plant officials said. Authorities still aren’t sure what caused the blaze.

Melissa Suggs, a spokeswoman for the Carlsbad Medical Center, said six patients were brought to the hospital from the plant to be treated for smoke inhalation. “They are all listed in stable condition,” she said.

Emergency officials say all waste handling operations were suspended and rescue teams were activated.

The Carlsbad Current-Argus reports that officials said at a press conference the fire occurred on a salt haulage truck in the north mine and “fire suppression systems” immediately activated underground.

Nuclear waste is stored in the south mine, officials said.

The repository takes plutonium-contaminated waste from Los Alamos National Laboratory and defense projects. The waste is then buried in rooms cut from underground salt beds.

Rod McCullum, the director of used-fuels programs at the Nuclear Energy Institute, said WIPP is the nation’s only deep geological nuclear repository and its license gets renewed by the federal Environmental Protection Agency every five years.