Two people have been killed and one injured after a gunman opened fire before taking his own life at Pearl Harbour military base in Hawaii.
Military officials confirmed that a US Navy sailor had attacked three Department of Defense employees before committing suicide.
The injured victim, a 36-year-old man, is in a stable condition in hospital while the attacker died from "an apparent self-inflicted gunshot wound", officials said.
A military spokesman said the situation has been “contained”. One witness saw the attacker shoot himself at the scene.
The Pearl Harbour Naval Shipyard was locked down on Wednesday afternoon after the shooting which is believed to have started at 2.30pm local time (10.30pm GMT). A PA system at the base urged people to take cover while staff received text messages alerts telling them to stay inside or find a secure location.
The shooting took place at Dry Dock 2, near the south entrance of a combined US Air Force and Navy base about 8 miles (13 km) from Honolulu.
Rear Admiral Robert Chadwick, commander of the Navy in Hawaii, said: “Our thoughts are with the families of the victims and everyone involved. This is certainly a tragedy for everyone here.”
He said it was not yet clear whether the gunman, a sailor assigned to the USS Columbia, knew the victims, who were all shipyard employees.
While the investigation into this incident continues, my thoughts and aloha are with the victims of the terrible tragedy at #JBPHH and with their families. I join all of Hawaii in expressing our gratitude to the first responders who rush toward danger every day to keep us safe— Senator Mazie Hirono (@maziehirono) December 5, 2019
One witness, who said he saw the gunman kill himself, told Hawaii News Now that he heard loud pops. “I kind of recognise that as gunshots,” he said. “I looked out the window and saw three people on the ground.”
“I looked out in time to see the shooter - who I assume was a sailor because he was in uniform - shoot himself.”
Base security forces posted on Twitter that they had closed all access gates to the shipyard while they investigated the incident.
David Ige, the governor of Hawaii, said the White House has offered assistance.
“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,” Mr Ige said.
A White House spokesman said: "The president has been briefed on the shooting at Joint Base Pearl Harbour-Hickam in Hawaii and continues to monitor the situation."
The incident comes three days before the anniversary of the attack on the naval base on December 7, 1941 that led the United States to enter World War Two by declaring war on Japan.