TheBakersfieldCalifornian.com

QUANTICO, Va. -- A Marine who worked at an officer candidates school fatally shot two of his colleagues before killing himself in a barracks dorm room, officials said.

The Marine's colleagues were a man and a woman. Military officials did not release a motive or the identities of those slain.

Authorities were called at the Marine Corps Base Quantico in northern Virginia around 10:30 p.m. Thursday and found one Marine dead in the Taylor Hall barracks, base commander Col. David W. Maxwell said. A second victim was found elsewhere in the barracks. The body of the gunman was also located in Taylor Hall.

It wasn't immediately clear how much time passed between the killings or how far apart the bodies were found.

Only staff for the school live in Taylor Hall, a red brick building on the base that can house about 110 Marines. The officer candidates live elsewhere.

The base was put on lockdown after the first shooting and Marines and their families were told to stay inside over a loudspeaker known as the Giant Voice. The lockdown was lifted early Friday.

Officials said all three Marines were staff members at the school, but their jobs were not released. Base spokesman Lt. Agustin Solivan said everyone else was safe, including the officer candidates.

The shooting is the second tragedy the Marine Corps has faced this week. Seven members of the 2nd Marine Expeditionary Force were killed Monday when a mortar shell exploded in its firing tube during an exercise at Hawthorne Army Depot in Nevada. Eight others were injured.

Pentagon press secretary George Little said Defense Secretary Chuck Hagel was saddened to learn of the shooting.

"This tragedy, as well as the tragedy in Nevada earlier this week, took the lives of Marines who volunteered to serve their nation," Little said. "His heart and his prayers are with them and their families."

The sprawling Quantico base, which is 37 miles south of Washington, is also home to the FBI's training academy.

The officer candidates school's 10-week program trains Marines in the classroom and uses endurance hikes and obstacle courses to evaluate leadership potential. Candidates must also demonstrate a grasp of battlefield-tested leadership traits, the Marine Corps website said.

When they graduate, the Marines become second lieutenants.

In 2010, the Quantico base was one of several targets of an ex-Marine reservist who, during five nighttime shootings, fired on military targets including the Pentagon. Yonathan Melaku, on two separate occasions, fired at the National Museum of the Marine Corps in Quantico. No one was injured and Melaku was sentenced to 25 years in prison.