A sailor of a U.S. submarine who shot three civilian employees and fatally shot himself at a Pearl Harbor Naval Shipyard has been identified as Gabriel Romero, according to The Associated Press and other sources.

The shooting occurred at Drydock 2 Wednesday afternoon.

Two male civilian employees were killed in the shooting and a third man, 36, was taken to The Queen’s Medical Center where his condition improved to stable condition from guarded condition.

He remained in stable condition this morning, according to a hospital spokeswoman.

The base was put on lockdown as military security forces as well as multiple law enforcement agencies and emergency medical responders arrived on scene.

Romero was assigned to the USS Columbia, a Pearl Harbor-based submarine that was in drydock for maintenance.

The 22-year-old shooter “opened fire on shipyard personnel with his M4 service rifle and then turned his M9 service pistol on himself,” Fox News Pentagon reporter Lucas Tomlinson reported, citing a preliminary incident report.

The circumstances leading up to the shooting are under investigation.

Tara Kapoi told The Associated Press that her 30-year-old husband, Vincent Kapoi Jr., was one of those killed. She said he worked at the shipyard and grew up in Waianae. “We don’t know what happened,” she said today, asking for privacy.

Names of the other victims have not been released.

The civilian employees belonged to the International Federation of Professional and Technical Engineers (IFPTE) Local 121 union. In a statement today, the the union extended their condolences to the family members of the shooting victims.

“These victims are not only dedicated IFPTE union members, they are hard-working public servants who go to work each day to serve the taxpayers and our military forces. They are reflective of the thousands of workers at Pearl Harbor and elsewhere that go to work to earn a living and serve their nation,” the organization said. “No worker should have to go to work without the expectation of safely returning to their family and loved ones.”

Meanwhile, the all clear for Joint Base Pearl Harbor-Hickam was given Wednesday evening and normal operations are to resume with exception to shipyard non-essential personnel, according to a post this morning in the Navy Region Hawaii Facebook page.

A statement issued by the White House late Wednesday said, “The President has been briefed on the shooting at Joint Base Pearl Harbor-Hickam in Hawaii and continues to monitor the situation.”

Capt. Greg Burton, commander of the Pearl Harbor Naval Shipyard, issued a message to shipyard personnel that was posted on Facebook in the wake of the deadly shooting Wednesday.

“Today we lost two of our shipyard civilians with another seriously injured in a tragic event this afternoon. I know that no words will convey the full measure of sorrow from today’s tragedy. This loss will be felt throughout our shipyard ‘Ohana, greater shipyard & NAVSEA family, submarine force, and the Navy as a whole,” Burton said.

“Looking ahead, we will honor the life and legacy of those lost. Even now, as we mourn the loss of members of our ‘Ohana, please take the opportunity to reconnect with each other and to reinforce and strengthen the bonds with each other. We value each one of you deeply and we are here for you,” he added.

The Associated Press contributed to this report.