Pearl Harbor Military Base
Three civilians were arrested at Hawaii's Joint Base Pearl-Harbor-Hickam after a security guard spotted a live mortar round in a vehicle waiting to enter the main gate late Tuesday, military officials said.

The guard at the main Nimitz Gate had ordered the vehicle to turn around when he detected the smell of marijuana and saw the ordnance in plain sight, according to spokesman Charles Anthony. The vehicle was attempting to enter the base without authorization.

An Explosive Ordnance Disposal team safely removed the round that Anthony described as "an explosive device" and "a deadly weapon." He said no firing device was found in the car and it is unknown how the men obtained the device.

Anthony said the round could be modified and triggered by something other than a traditional mortar tube, but no detonation system was found in the vehicle.

A base spokesman said the three occupants of the vehicle were civilians, Hawaii News Now reported. Anthony said the individuals were in the custody of the Naval Criminal Investigative Service.

All gates to the base were closed for about two hours, according to a statement.

Anthony said hundreds of people, usually lost, end up at the base gate each day and are turned around if they do not have authorization to enter.

In December, an active-duty U.S. sailor opened fire on three civilian employees at the base's naval shipyard, killing two of them. Officials have said the sailor, whose submarine was docked at Pearl Harbor, then took his own life.

The shooting happened days before dignitaries and veterans attended the base's ceremony to mark the 78th anniversary of the Japanese attack on Pearl Harbor.

In a separate incident, a lockdown ended at Tennessee's McGhee Tyson Air National Guard Base on Wednesday afternoon after a report of a suspicious person who appeared to be armed turned out to be a misunderstanding, officials said.

A student had reported seeing a suspicious person with what looked like a weapon, said Lt. Col. Travers Hurst, a spokesman at the airbase near Knoxville.

There has been heightened concern about gun violence on military bases after shootings at military installations in Florida and Hawaii killed five people in December.