Investigators believe a massive fire that erupted on the Navy ship the USS Bonhomme Richard may have been intentionally set, and a sailor has been identified as a possible suspect, two defense officials confirmed Wednesday.
The new details in the investigation of the July fire were reported Wednesday by KGTV-TV of San Diego, where the amphibious assault ship is based.
Two defense officials confirmed to NBC News that investigators now suspect arson. But the investigation continues, and it has not been determined whether the sailor is an actual suspect.
The sailor was not named, and no additional details were released.
"The Navy will not comment on an ongoing investigation to protect the integrity of the investigative process and all those involved. We have nothing to announce at this time," Lt. Tim Pietrack, a Navy spokesman, said in an email Wednesday night.
The Naval Criminal Investigative Service, or NCIS, with assistance from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives' national response team, is investigating.
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The fire started July 12 and was extinguished four days later after having caused extensive damage.
The ship, an amphibious assault vessel that works to deploy elements of Marine landing forces, was based at Naval Base San Diego after having spent six years in Japan.
Adm. Michael M. Gilday, the chief of naval operations, has praised the work of more than 400 sailors from 16 ships based in San Diego who helped fight the fire, and he pledged a thorough investigation.
He has previously said that restoring the Bonhomme Richard to its status as an amphibious assault ship "could be too heavy a lift" but that there may be other options for how to restore it.
Eleven of the ship's 14 decks were "devastated by the fire," he said.
A Navy official said shortly after the fire was extinguished that if the ship were to be deemed unsalvageable, it would cost $4 billion to replace.
Damage assessment continues, Lt. Ryan Slattery, a Navy spokesperson, said in an email Wednesday.
"Naval Sea Systems Command (NAVSEA) is conducting thorough damage assessments to determine USS Bonhomme Richard's hull and structural integrity and identify which components and systems can be repaired or require replacement, as well as an estimate of repair costs," Slattery said.
"These assessments are ongoing, and NAVSEA's findings will allow the Navy to make informed cost and schedule decisions regarding the future of the ship," he said.
The Bonhomme Richard was nearing the end of a two-year upgrade estimated to cost $250 million when the fire broke out, NBC San Diego reported.
About 160 crew members were on board when the fire started. All were accounted for.
More than 60 sailors and civilians suffered what were described as minor injuries, including heat exhaustion and smoke inhalation, before the fire was extinguished.
An NCIS spokesman said that out of respect for the investigative process, the agency does not comment on or confirm details related to ongoing investigations.