Son of former MLB player Steve Sax among 5 Marines killed in training flight crash

The son of former MLB player Steve Sax was one of five Marines killed when their military aircraft crashed during routine flight training this week, the family confirmed Saturday.

Capt. John J. Sax, 33, and four other Marines from the 3rd Marine Aircraft Wing died when their MV-22B Osprey -- a hybrid airplane and helicopter -- crashed in a remote, desert area of Southern California near Glamis on Wednesday.

"It is with complete devastation that I announce that my precious son, Johnny, was one of the five U.S. Marines that perished," Steve Sax said in a statement.

Steve Sax called his son a "hero and the best man I know."

"For those of you that knew Johnny, you saw his huge smile, bright light, his love for his family, the Marines, the joy of flying airplanes and defending our country," he continued.

John Sax served in the Marines for over five years and had been awarded the National Defense Service Medal, Global War on Terrorism Service Medal and a Letter of Appreciation, his family said.

Ahead of Veteran's Day last year, Steve Sax proudly spoke about being the father of a Marine and about the intense training his son had undergone to become a captain.

"What he's done -- to sacrifice himself -- is unbelievable," Steve Sax said on his podcast, "Sax in the Morning." "Just know this. I know my son, and I know that you people can rest assured that he would give his life so that you can have your freedom."

Steve Sax, an All-Star second baseman, was a two-time World Series champion with the Los Angeles Dodgers. The team expressed their condolences Saturday.

"The Los Angeles Dodgers are saddened to hear about the passing of Steve Sax's son, John, and the five Marines who lost their lives in this week's tragic helicopter accident," the team said in a statement.

John Sax was one of two MV-22B pilots killed in the crash, along with Capt. Nicholas P. Losapio, 31, of Rockingham, New Hampshire, the 3rd Marine Aircraft Wing said Friday. Three tiltrotor crew chiefs also died in the crash -- Cpl. Nathan E. Carlson, 21, of Winnebago, Illinois; Cpl. Seth D. Rasmuson, 21, of Johnson, Wyoming; and Lance Cpl. Evan A. Strickland, 19, of Valencia, New Mexico -- the 3rd Marine Aircraft Wing said.

All were based at Marine Corps Air Station Camp Pendleton in California and assigned to Marine Medium Tiltrotor (VMM) Squadron 364.

"It is with heavy hearts that we mourn the loss of five Marines from the Purple Fox family," Lt. Col. John C. Miller, commanding officer of VMM-364, said in a statement. "This is an extremely difficult time for VMM-364 and it is hard to express the impact that this loss has had on our squadron and its families."

The cause of the crash is under investigation.

ABC's Aaron Joey Wahler reports for ABC News Radio:

ABC News' Izzy Alvarez contributed to this report.