Updated

Joint Base Pearl Harbor-Hickam issued an "all clear" Tuesday evening hours after residents and employees were ordered to shelter in place over a "potential security incident" at the Hawaiian military base.

The lockdown was ordered around 9:39 a.m. local time in response to an unspecified security incident. 

Units from Honolulu Police Department and Federal Fire Department responded to assist JBPHH security and other emergency personnel in the investigation. 

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JBPHH said in a statement provided to Fox News that the base remained fully operational while the Emergency Operations Center was manned to coordinate a response to the threat. 

Tours to the USS Arizona Memorial and other historic partners were suspended but have since resumed. Guests at the USS Missouri Memorial and the Pearl Harbor Aviation Museum on Ford Island were also ordered to shelter in place. Tours have since resumed. 

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"We are grateful to the first responders who helped us investigate and secure the potential incident," said Col. Tammie Harris, Deputy Joint Base Commander. "I want to assure everyone that we will do everything possible to maintain the operational readiness of JBPHH while protecting the safety of our base employees, our service members and their families."

David Hodge, a JBPHH spokesman, told the Air Force Times that the security incident was "an actual situation" and not part of an exercise. 

The exact nature of the security threat that prompted the shelter-in-place order remains unclear.