WASHINGTON A Marine shot dead a male and female colleague at a Virginia base and then killed himself, in the second fatal non-combat incident involving Marines in the United States this week.
Military investigators declined to comment on what motivated the shooting late on Thursday, which led to a 3-1/2 hour lockdown of Marine Corps Base Quantico that extended to the pre-dawn hours on Friday.
The shooter and his victims were school staff members and active-duty Marines, base commander Colonel David Maxwell said on Friday.
"This is a tragic loss for our Marine Corps family," Maxwell told a news conference.
The shooting took place at Taylor Hall, a barracks at the base's Officer Candidates School, about 40 miles south of Washington, Maxwell said. The base is known as "the Crossroads of the Marine Corps."
Base security officers received a 911 call at about 10:30 p.m. on Thursday and responded within five minutes, backed up by local police, Maxwell said. They fired no shots.
Base officials said they would not release the identities of the dead until 24 hours after their relatives were notified.
The incident was initially reported as a standoff, with the suspect barricaded, but Maxwell said it was not.
Military officials did not comment on what may have motivated the shooting. Asked if a relationship dispute could have prompted the incident, Staff Sergeant Brian Kester said, "Not to my knowledge."
The Officer Candidates School provides basic instruction for prospective Marine officers. The sprawling Quantico base is also home to the Marine Corps' brig and museum.
It was the second fatal incident for Marines on U.S. soil this week. Seven died on Monday when a mortar exploded at an munitions depot in Nevada during a live-fire training exercise.
Eight other service members were wounded in that mishap, which prompted the Marines to suspend use of 60mm mortars pending a review.
The U.S. military is also grappling with an increase in suicides. The armed forces said in January that suicides by active-duty personnel numbered a record 349 last year, more than died in combat.
The Army on Friday reported 31 potential active-duty suicides this year through February. Ten had been confirmed as suicides and 21 were under investigation, it said in a statement.
The House of Representatives' Armed Services Committee on Thursday had discussed how access to firearms contributes to the risk of suicide among active-duty soldiers.
Most military suicides are by enlisted white males 29 and younger. The Pentagon has distributed more than 70,000 gun locks to combat suicides, Jacqueline Garrick, acting director of the Defense Suicide Prevention Office, told the panel's military personnel subcommittee.
"Everyone in the Department fervently believes that even one life lost to suicide is one too many and prevention is everyone's responsibility," Garrick said in prepared remarks.
(Additional reporting by Cynthia Johnston in Las Vegas and Phil Stewart in Washington; Editing by Scott Malone, Alden Bentley, Gary Hill)