"We are sad to report that both aviators have been declared deceased," a statement posted to the Naval Air Forces Twitter account read. "Their families are in our prayers. Per policy, we will withhold notification pending [next-of-kin] notification."
No further information was available about the nature of the pilots' injuries.
The statement came roughly 6 hours after the aircraft crashed on final approach to Boca Chica Field following a training mission.
A spokesman with Naval Air Forces Atlantic, Cmdr. Dave Hecht, told Military.com earlier in the day that a pilot and weapons systems officer had been transferred to Lower Keys Medical Center in Key West after aircraft, assigned to Strike Fighter Squadron 213, out of Naval Air Station Oceana, Virginia, suffered a mishap approximately a mile off the runway.
Elements of the squadron, nicknamed the Blacklions, had been completing a detachment to Naval Air Station Key West.
The crash happened around 4:30 p.m., Hecht said. Both pilots onboard the Super Hornet ejected, he said. Initially, Hecht said a search-and-rescue effort for the aircrew was still ongoing around 6 PM, but later he said the pilots were recovered within minutes and taken by ambulance to the medical center.
An eyewitness, Barbie Wilson, told Military.com the crash "looked like something out of a movie."
Wilson, who lives on the back side of the air station, said she stopped to watch an F/A-18 flying overhead, as she often does, and was shocked to see what appeared to be a massive malfunction in midair.
"Literally, the wings went vertical, and there was a fireball, and it just literally dropped out of the sky," Wilson said.
She said she didn't see the plane hit the water, but observed the crash site in shallow water offshore. Wilson said she can still see the wreckage of the plane upside down in the water.
She did not observe the pilots ejecting from the aircraft, she said. A helicopter that appeared to be part of the search mission was circling overhead, she added.
It's not clear what caused the crash.