A mysterious object crashed just outside Nevada’s secretive Area 51 on September 23, prompting a swift and secretive military response.

Witnesses reported that the base and surrounding Tiikaboo Valley were locked down as armed patrols blocked roads and helicopters moved in to recover debris.

The Air Force later claimed the wreckage belonged to an unmanned aircraft from Creech Air Force Base, but independent observers and local researcher Joerg Arnu say that explanation doesn’t add up, 8 News Now has reported.

Investigators believe the craft may have been part of an advanced AI-controlled drone program, though the true nature of what crashed remains unknown.