This post has been updated with additional information.

A sailor assigned to USS Theodore Roosevelt (CVN-71) has died from complications of a COVID-19 infection and four more are hospitalized, the Navy said on Monday.

“At approximately 8:30 a.m., Apr. 9, the Sailor was found unresponsive during a daily medical check. While Naval Base Guam emergency responders were notified, CPR was administered by fellow Sailors and onsite medical team in the house,” read a statement from the service. “The sailor was transferred to U.S. Naval Hospital Guam where the sailor was moved to the Intensive Care Unit (ICU). The sailor was declared deceased April 13.”

The service is withholding the identity of the sailor until 24 hours after next-of-kin notification. In addition, four Roosevelt sailors were hospitalized over the weekend.

“All are in stable condition, none are in ICU or on ventilators,” a Navy official told USNI News.

The service has tested 92 percent of the sailors assigned to Roosevelt and discovered 585 positive cases of the virus. 3,921 sailors have tested negative since the carrier pulled into Guam last month, according to Navy data released Monday.

In total 4,021 sailors have been moved to shore on Guam and are all in various stages of a 14-day isolation period in hotels and spare rooms across the island.

Infections on Roosevelt account for 63 percent of the Navy’s 929 active duty COVID-19 cases. Of the sailors who have tested positive, almost 70 percent have been asymptomatic, a Navy official told USNI News on Monday.

The death of the sailor marks the first active duty U.S. service member to die from COVID-19. In late March, Army National Guard Capt. Douglas Linn Hickok, 57, died from the virus.

“We mourn the loss of the sailor from USS Theodore Roosevelt who died today, and we stand alongside their family, loved ones, and shipmates as they grieve,” Chief of Naval Operations Adm. Mike Gilday said in a Monday statement. “My deepest sympathy goes out the family, and we pledge our full support to the ship and crew as they continue their fight against the coronavirus. While our ships, submarines and aircraft are made of steel, Sailors are the real strength of our Navy.”

Acting Navy Secretary James McPherson issued a statement mourning the loss.

“We will never forget their service and sacrifice to our nation. My thoughts are also with the Sailor’s shipmates, and the families of the entire crew. I am keenly aware of the dedication and commitment of our sailors and Marines in service to our nation – in war, peace, and this unfamiliar time of COVID-19. I will continue to do everything in my power to support their efforts and safety as we respond as one nation to this pandemic,” he said.

The outbreak on Roosevelt is being carefully studied by the service as it prepares to deploy its first major formations since the pandemic took hold in the U.S.

“What we’ve learned, certainly in the Navy, is that with regard to COVID 19, we’re learning that stealth in the form of asymptomatic transmission is this adversary’s secret power,” said Rear Adm. Bruce Gillingham, the surgeon general of the Navy, during a briefing last week. “We recognize despite really our best efforts we’re going to have to learn how to operate with the virus.”

Major formations preparing to deploy are adapting to new procedures.

Carrier USS Nimitz (CVN-68) in Washington state and Carrier Air Wing 17 in California are in their 13th day of a so-called 14-day restriction of movement (ROM) period with the crews subjected to daily medical evaluations.

Still, the procedures have been put in place to make up for the lack of accurate testing across the Pentagon and the Navy.

“The constraint of the current testing technology is you may test negative, but the testing is not so accurate to say that you know that, that person is negative,” Thomas McCaffery, the assistant Secretary of Defense for health affairs, said last week.

“We do know we have folks who are asymptomatic, who may have tested negative, who are infected.”

The following is the complete April 13, 2020 statement from the Navy.

PEARL HARBOR (NNS) — The Sailor assigned to the USS Theodore Roosevelt (CVN 71) who was admitted to the Intensive Care Unit (ICU) of the U.S. Naval Hospital Guam April 9 (local date) died of COVID-related complications on April 13.

The name of the Sailor is being withheld until 24 hours after next-of-kin notification.

The Sailor tested positive for COVID-19 March 30, was removed from the ship and placed in an isolation house on Naval Base Guam with four other USS Theodore Roosevelt (CVN 71) Sailors. Like other Sailors in isolation, he received medical checks twice daily from Navy medical teams.

At approximately 8:30 a.m., Apr. 9 (local date), the Sailor was found unresponsive during a daily medical check. While Naval Base Guam emergency responders were notified, CPR was administered by fellow Sailors and onsite medical team in the house. The Sailor was transferred to U.S. Naval Hospital Guam where the Sailor was moved to the Intensive Care Unit (ICU). The Sailor was declared deceased April 13.

USS Theodore Roosevelt arrived in Guam on 27 March for a scheduled port visit for resupply and crew rest.