NBC's Jim Miklaszewski says: A U.S. Marine reservist and a Navy corpsman were killed in a drone airstrike in Afghanistan last week in an apparent case of friendly fire, U.S. military officials tell NBC News.

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Sailors salute as seaman Benjamin Rast's flagged-draped coffin is removed from the airplane at South Bend Regional Airport in South Bend, Ind. The military says Rast a 23-year-old Navy medic of Niles, Mich., died April 6 while on patrol in Afghanistan's Helmand province.

Marine Staff Sgt. Jeremy Smith and Navy Corpsman Benjamin Rast were reportedly killed Wednesday by a Hellfire missile fired from a U.S. Air Force Predator in what appears to be a case of mistaken identity, NBC reported. Smith and Rast were part of a Marine unit moving in to reinforce fellow Marines under heavy fire from enemy forces outside Sangin in Helmand province in southern Afghanistan.

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Robert Rast salutes as his son's flagged-draped coffin is removed from the airplane at South Bend Regional Airport in South Bend, Ind.

The Marines under fire were watching streaming video of the battlefield being fed to them by an armed Predator overhead. They saw a number of "hot spots," or infrared images, moving in their direction. Apparently believing that those "hot spots" were the enemy, they called in a Hellfire missile strike from the Predator.

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Members of the Patriot Guard escort the funeral procession for sailor Benjamin Rast from the South Bend Regional Airport in South Bend, Ind.

It's believed that this is the first time that U.S. service members have been killed by a Predator in a friendly fire incident.

Smith, 26, of Arlington, Texas, was assigned to the 1st Battalion, 23rd Marine Regiment, 4th Marine Division out of Houston. Rast, 23, was assigned to the 2nd Marine Division out of San Diego.

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Students from nearby St. Bavo Elementary School line the street outside Hahn Funeral home to show their respect Rast.

The U.S. military is investigating the incident. Military officials say the families of both service members have been informed of the possibility this was a friendly fire incident.

Robert Franklin / South Bend Tribune via AP

St. Bavo first grader and boy scout Nathan Watt salutes as the coffin carrying the body of sailor Benjamin Rast is transported inside Hahn Funeral home in Mishawaka.