Officers rushed into the north yard of Mansfield Correctional Institution in Mansfield, Ohio, last week after noticing 75 inmates gathering and a fight breaking out, according to an incident report from the Ohio Department of Rehabilitation and Correction.
Authorities later reviewed surveillance tapes and found that a drone had flown over the yard and dropped a package.
Officers had to use pepper spray to get the situation under control, The Columbus Dispatch reported. Inmates were later strip-searched before being allowed to return to their cells.
Nine inmates were placed in solitary confinement following the incident on July 29.
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Authorities later found the package in an equipment room in the southern part of the facility, the report says.
Ohio authorities are now on the lookout for more attempts to use drones to smuggle drugs over prison walls and into inmates hands.
"It's something we're certainly aware of," Smith said. "We're taking a broad approach to increasing staff awareness and detection," CNN quoted her as saying.