It’s a given that joining the military can mean putting one’s life in danger. However, that danger isn’t generally assumed to be great while training on home soil.

Two U.S. Navy divers recently proved that even training is dangerous, and even fatal, as they drowned while training in a Maryland test pond. According to a Baltimore Sun report, Diver 1st Class James Reyher and Diver 2nd Class Ryan Harris accidentally drowned at a test pond at the Aberdeen Proving Ground in February. Details of the incident have not been released.

Another soldier, an engineering technician, also died at the test pond in January while performing maintenance. The facility has now been closed indefinitely.

The pool where the soldiers drowned is, according to the Sun, also known as the “Super Pond.” The structure is 1,070 feet long and 150 feet deep. It is used by the U.S. Defense Department and researchers for training and to test the effects of explosives on marine vessels.

The investigations of the soldiers’ deaths are still ongoing, and the Office of the Chief Medical Examiner has stated that more information about the incidents could be released in the future, when the office issues its final report.