A US sailor fatally shot two people and wounded a third at the Pearl Harbor Naval Shipyard in Hawaii on Wednesday before taking his own life, a senior Navy officer said.

The base was locked down for more than an hour after the shooting, according to a statement issued by the facility, while Navy officials said they were investigating what prompted the attack.

"I can confirm that there were three shooting victims. We have confirmed that two are deceased, one is in stable condition in a local hospital," said Rear Admiral Robert Chadwick.

He added that the shooter - "tentatively" identified as a sailor assigned to the USS Columbia, a Los Angeles-class attack submarine - had also died after "an apparent self-inflicted gunshot wound."

One witness told local media he was sitting at his computer when he heard shots fired and rushed to the window, where he saw three victims on the ground.

The witness, who did not want to be identified, said he then saw the gunman, who was wearing a sailor's uniform, shoot himself in the head.

White House spokesman Hogan Gidley said that US President Donald Trump had been briefed on the shooting and was monitoring the situation.

Hawaii governor David Ige tweeted that the "White House has reached out to offer assistance from federal agencies, and the state is standing by to assist where necessary."

"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 wrote.

Copyright Agence France-Presse, 2019