Military Casualties

The incident is under investigation, according to the Department of Defense.

This year's casualty count now matches the total for 2018, previously the deadliest year for Operation Freedom's Sentinel.

The deaths of U.S. Master Sgt. Jonathan Dunbar and British Sgt. Matthew Tonroe in Syria were "not by enemy action."

Spc. Ryan Riley, 22, died in Ninawa province, Iraq.

The Marines were killed near Bagram Air Base when an improvised explosive device hit their convoy.

Maj. Matthew M. Wiegand, 34, and Capt. Travis W. Brannon, 30, died in the crash, Marine officials said Monday.

The pilots were flying an AH-1Z Viper helicopter.

"He had that split second to make that decision ... to sacrifice himself so that we could all live."

The soldiers were killed Friday in Kunduz province, Afghanistan.

Navy SEAL Remington J. Peters had completed more than 600 jumps with the Navy's elite Leap Frogs parachute team.