A U.S. Military Academy Class of 1987 graduate and former tactical officer was among the six soldiers killed in Monday’s crash of two 25th Infantry Division (Light) Aviation Brigade UH-60 Blackhawk helicopters in Hawaii.

Maj. Robert L. Olson and the five other soldiers killed in the crash were aboard the same helicopter. Of the 11 other soldiers injured, four were listed in stable condition at Tripler Army Medical Center Tuesday, and the other seven were treated for minor injuries and released.

"Our deepest heartfelt condolences go out to the families of these soldiers at this moment of grief and sorrow," said Maj. Gen. James Dubik, the commander of the 25th Infantry Division (Light) and U.S. Army Hawaii. "At this time, our focus is on taking care of the families and ensuring the injured soldiers receive the best possible medical attention."

Olson served as the tactical officer for U.S. Corps of Cadets Company E2 from 1997-1999 after reporting to West Point in 1996 for a year of graduate school in the Tactical Officer Education Program. He left West Point in 1999 to attend Command and General Staff College before reporting to Hawaii last year to serve as the training and operations officer for the 2nd Battalion, 11th Field Artillery.

"His loss is a tremendous loss to the Army community," said Col. Joe Adamczyk, the USCC brigade tactical officer. "He was a superb officer -- a professional in every sense of the word."

Olson’s wife, Maj. Holly Olson, a physician, is also a 1987 USMA graduate and served at Keller Army Community Hospital here in the Obstetrics/Gynecology Clinic.

Adamczyk said the Olsons were "outstanding citizens of the West Point community."

Olson’s unit was conducting an infantry brigade combat team field exercise in the U.S. Army Kahuku Military Training Area in the northern part of Oahu. More than 3,500 soldiers were participating in the exercise.

The helicopters that Olson and 16 other soldiers were aboard "somehow came in contact" with each other, but it was unclear whether they collided in the air, Pentagon spokesman Navy Adm. Craig Quigley said in a Tuesday press conference.

The cause of the accident is under investigation, and investigators from the Army Safety Center, Fort Rucker, Ala., were scheduled to be on scene at the crash Tuesday.