PEARL HARBOR, Hawaii — An active duty U.S. sailor whose submarine was docked at Pearl Harbor opened fire on three civilian employees Wednesday, killing two and then taking his own life just days before dignitaries and veterans descend on the base for the 78th anniversary of the Japanese attack.

The commander of Navy Region Hawaii, Rear Adm. Robert Chadwick, said he didn’t know the motive behind the shooting at the Hawaii base’s naval shipyard that left the third civilian Department of Defense employee hospitalized.

It also wasn’t known if the sailor and the three male civilians had any type of relationship, or what the motive was for the shooting, Chadwick said.

“We have no indication yet whether they were targeted or if it was a random shooting,” Chadwick said.

The sailor was assigned to the fast attack submarine USS Columbia, which is at Joint Base Pearl Harbor-Hickam for maintenance. Details about the sailor were not immediately released.

It wasn’t immediately known what type of weapon was used or how many shots were fired. Chadwick said that was part of the investigation. Personal weapons are not allowed on base.

Names of the victims won’t be released until next of kin have been notified.

“Our thoughts are with the families of the victims and everyone involved. I can say that we are mobilizing support services for naval shipyard personnel as well as everyone else who may be affected by this tragic event,” Chadwick said.

The base went into lockdown around 2:30 p.m. when the first active shooter reports were received. The base reopened a few hours later. Witnesses were still being interviewed hours after the shooting.

The shipyard repairs, maintains and modernizes the ships and submarines of the U.S. Pacific Fleet, which is headquartered at Pearl Harbor. The base is the home port for 10 destroyers and 15 submarines. It also hosts Air Force units.

Hawaii Gov. David Ige said the White House has offered assistance from federal agencies and that the state is also ready to help if needed.

“I join in solidarity with the people of Hawaii as we express our heartbreak over this tragedy and concern for those affected by the shooting,” Ige said in a statement.

The shipyard is across the harbor from the Pearl Harbor National Memorial, which on Saturday will mark the 78th anniversary of the Japanese bombing that propelled the U.S. into World War II. More than 2,300 Americans died in the attack on Dec. 7, 1941.

The shipyard has played a key role in naval history, most notably during World War II. Shipyard workers were given just days to repair the USS Yorktown, an aircraft carrier severely damaged during the Battle of the Coral Seat in 1942 because the Navy needed to quickly send the ship to Midway to meet Japanese forces there.

Some 1,400 shipyard workers labored around the clock for almost 72 hours to patch the carrier together. The planes the Yorktown delivered to Midway sank one of the four aircraft carriers Japan sent to the battle and helped destroy two others. The Battle of Midway turned the tide of the war in the United States’ favor.

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