Emergency responders were on the scene of an incident at the Nevada National Security Site on Tuesday afternoon, the National Nuclear Security Administration reported.
According to a spokesperson, an unknown device was discovered outside the fence surrounding a device assembly facility. Response teams later determined the device was harmless.
All employees were accounted for and operations have resumed.
The Nevada National Security Site, formerly known as the Nevada Test Site, is located about 65 miles northwest of Las Vegas and was used for nuclear testing in decades past.
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