The U.S. Army has concluded that the death of a civilian diver at Aberdeen Proving Ground earlier this year was accidental, according to a report obtained by the Associated Press.

George H. Lazzaro Jr., 41, died Jan. 30 while performing routine maintenance in the underwater test facility known as the Super Pond. Lazzaro, a former Marine who lived in Baltimore County, was the first of three divers to die in the Super Pond in less than a month. Navy Diver 1st Class James Reyher, 29, and Diver 2nd Class Ryan Harris, 22, drowned Feb. 26 while training.

Lazzaro's death was most likely the result of his rapid ascent to the water's surface as he began to lose air, according to the report from the Army Safety Center, obtained by the AP. He had air bubbles in his lungs, heart, brain and veins, which happens when a diver holds his breath while surfacing quickly, the AP reported.

The U.S. Occupational Safety and Health Administration in August found multiple serious safety violations at the Super Pond after it investigated Lazzaro's death. The Super Pond, officially known as the Underwater Explosion Test Facility, is used to conduct underwater shock tests of marine vessels without harming aquatic creatures.

OSHA found seven serious violations, meaning there was "substantial probability that death or serious physical harm could result from a hazard about which the employer knew or should have known." The violations included not leaving a qualified person above the water to supervise the dive, keeping no reserve air supply and having no standby diver. OSHA said at the time it issued its notices that such tragedies are preventable.

Lazzaro's team members said they heard a member of the team say "I'm losing air," then saw bubbles, the AP reported. Lazzaro surfaced before removing his mask and sinking again.

Eloise Lundgren, a spokeswoman for the Army Test and Evaluation Command, said that based on recommendations from the Army Safety Center and OSHA, the command and Aberdeen test center are "incorporating appropriate measures" to include use of the Navy dive manual, use of Navy divers and changes to standard operating procedures that she said she could not detail for "operational security" reasons.

While the Army has concluded that no one should face charges in Lazzaro's death, four Navy sailors face trial over the deaths of divers Reyher and Harris, while a fifth opted for administrative discipline.