It’s not clear why the group had the explosive device, which authorities said did not have a firing device attached but could be modified and triggered by something other than the usual mortar tube. A spokesman for the Hawaii base called the device a “deadly weapon.”

The trio were stopped on their way into the sprawling base by security on Tuesday night after a guard smelled marijuana, leading him to look closer at the inside of the vehicle and spot the “potential ordnance,” the spokesman said. The base was shut down for approximately two hours while a bomb squad investigated and reopened with no injuries.

Naval Criminal Investigative Service arrested the suspects and is looking into the incident, which comes just a month after a US sailor went on a shooting rampage inside the Pearl Harbor Naval Shipyard, killing two civilian workers and injuring one more before shooting himself.

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