An F-35B Lightning II launches from the amphibious assault ship USS Essex on Sept. 22, 2018. (U.S. Marine Corps/Cpl. Francisco J. Diaz, Jr./AFP/Getty Images)

The U.S. military suffered its first crash of an F-35 aircraft in the 17 year history of the high-profile fighter jet program, the same day the Pentagon announced it had struck a deal with defense contractor Lockheed Martin to drive down costs for the next batch of planes to a historical low.

The crash of the Marine Corps variant of the F-35, known as the F-35B Lightning II, occurred Friday at 11:45 a.m. outside Marine Corps Air Station Beaufort in South Carolina, according to the Marine Corps. The service did not give a suspected cause for the crash, saying the incident remained under investigation.

“The U.S. Marine pilot safely ejected from the single-seat aircraft and is currently being evaluated by medical personnel,” the Marines said in a statement. “There were no civilian injuries.”

The aircraft, which cost more than $100 million, belonged to Marine Fighter Attack Training Squadron 501, which trains Marine pilots for combat with the F-35.

In the past, F-35 jets have made emergency landings, experienced in-flight incidents, including oxygen deprivation among crews, and suffered from engine fires and other failures on the ground. But this is the first time the military has suffered a full-blown crash of an F-35 involving the ejection of a pilot.

A U.S. military official, who spoke on the condition of anonymity because the investigation remained underway, said the Marine Corps initially classified the crash as a Class A mishap, which is defined as an incident resulting in the complete destruction of the plane, more than $2 million in damage or the fatality or permanent total disability of the crew.

The Pentagon’s deal with Lockheed Martin for 141 fighter jets comes amid persistent controversy over a weapons program that has become the most expensive the Defense Department has ever undertaken.

The most common variant of the Joint Strike Fighter, known as the F-35A, dropped below $90 million per unit for the first time, to $89 million, a 5.4 percent decrease from the previous lot. The price per unit for the Marine Corps and Navy versions dropped to $115 million and $108 million, respectively.

President Trump has pushed Lockheed Martin for lower costs and taken credit for hundreds of millions of dollars in savings, though the F-35 unit price was projected to decrease as the fighter jet transitioned from its development phase into production.

The Pentagon has attributed an increase in aviation accidents to a mix of causes, including years of stopgap funding from Congress, aging equipment, strained maintenance crews and reduced flying hours for pilots.

An investigation by the Military Times earlier this year found that Marine Corps aviation mishaps had jumped 80 percent over the last five years, an increase that came alongside similar trends in the Navy and Air Force

Defense Secretary Jim Mattis has vowed to sort out the issues using additional funding the Pentagon has received in the coming year’s $716 billion defense budget. Still, U.S. military officials have cautioned the incidents are the result of a range of issues that will take time to fix.

On Friday, the Marines said they were working with authorities in South Carolina to secure the crash site and guarantee the safety of all personnel in the surrounding area. The service did not give any details about the pilot or what happened ahead of the crash.