Two Marines were critically injured in a flash fire involving an F/A-18A jet late Sunday night at Marine Corps Air Station Miramar in San Diego, California, according to statements released by base officials.

The two injured Marines have not been identified, but are reported to belong to the Marine Fighter Attack Squadron 112 (VMDA-112), part of the 4th Marine Air Wing.  The VMDA-112 is a reserve unit out of Fort Worth, Texas, though there is no word as to whether the injured Marines were reservists.

Local media has reported that two Marine Corps mechanics were caught in what Miramar officials are calling a “ground flash fire” while working on the fighter jet.  An early version of the statement was released by base officials that called the incident an explosion, rather than a fire, but that release was promptly removed and replaced by an updated document.

“Technically, this was a ‘ground flash fire’ rather than an explosion,'” Major Kurt Stahl, the director of public affairs for the 3rd Marine Aircraft Wing, MCAS Miramar, explained to the press. “The cause is under investigation.”

A ground flash fire, by definition, differs from an explosion in their source, which requires an airborne fuel and ignition source.  According to the National Fire Protection Association, ground flash fires tend to last just seconds, but can reach extremely high temperatures.

The Naval Safety Center reported that the Marines were conducting maintenance on an F/A-18A fighter jet, when a flammable material in a “drip pan” ignited at approximately 10:18PM, engulfing both mechanics and causing significant damage to the aircraft. Investigators from the New Orleans-based 4th Marine Air Wing are on site and have already commenced a formal investigation into the cause of the blaze.

Maj. Kurt M. Stahl told reporters the blaze was completely extinguished “within minutes,” thanks to the air station’s Aircraft and Firefighting Rescue detachment’s prompt response.

The Marines have been transferred to UC San Diego Medical Center in Hillcrest for treatment and remain in critical condition.