Story highlights "We don't think there's any kind of threat," city manager says

City: Two chemicals were inadvertently mixed together, causing a reaction

(CNN) The plume has dissipated from a chemical spill that had spurred dire warnings Friday from officials in Atchison, Kansas, the city manager said.

"We don't think there's any kind of threat at this time and we're in the process of issuing an all-clear," City Manager Trey Cocking told reporters.

Authorities haven't released details about what kind of chemical leaked, but they've said residents who'd been advised to take shelter inside can now leave their homes.

The spill occurred during a delivery at a plant just after 8 a.m. (9 a.m. ET), when two chemicals were inadvertently mixed together, sending a gaseous plume into the air, Cocking said.

Images from CNN affiliate KSHB after the spill showed a thick gray plume clouding the air.

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