A US Navy sailor shot and killed two people at the historic military base at Pearl Harbor, Hawaii on Wednesday before fatally shooting himself, military officials said.
The shooter died from "an apparent self-inflicted gunshot wound". A third victim is in stable condition after being hospitalised.
"We have confirmed that two (victims) are deceased. One is in stable condition in a local hospital. I can also report that the shooter, who has tentatively been identified as an active-duty sailor assigned to USS Columbia SSN 771, is also deceased by an apparent self-inflicted gunshot wound," Rear Admiral Robert Chadwick said.
Joint Base Pearl Harbor-Hickam said earlier on Twitter that the three victims were all civilians working for the US Department of Defense.
"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," Governor David Ige said on Twitter.
"Details are still emerging as security forces at Joint Base Pearl Harbor Hickam investigate.
"The president has been briefed on the shooting at Joint Base Pearl Harbor-Hickam in Hawaii and continues to monitor the situation," a White House spokesman said.
The base, which was formed by the merger of Pearl Harbor Naval Station and Hickam Air Force Base, was placed on lockdown for about two hours following the incident at about 2:30 p.m. Hawaii time.
Joint Base Pearl Harbor-Hickam is a combined U.S. Air Force and Navy Installation located 13 km from Honolulu. The incident comes three days before the 78th anniversary of the December 7, 1941 attack on the naval base that led the United States to enter World War Two by declaring war on Japan.