At least 26 sailors at a shore-based Naval depot in Mumbai testing positive for Covid-19 has triggered a scare in the military establishment.

The crisis at INS Angre, which provides logistical and administrative support to the Western command’s naval operations, is the first major Covid-19 outbreak within India’s 15-lakh-strong armed forces.

It comes at a time the pandemic has hit the US and French navies’ operations.

Earlier, India’s army had reported eight patients, including two doctors, one each in Delhi and Calcutta.

“Most of (the 26 infected) are asymptomatic and (the infection has) been traced to a single sailor who tested positive on April 7,” a navy statement said on Saturday.

“They all stayed in the same accommodation block at INS Angre. Entire in-living block was immediately put under quarantine.”

The navy said all the primary contacts of the sailor who first tested positive had been tested for Covid-19.

An operation has been launched to trace everyone who may have come in contact with the 26 infected sailors.

The navy has clarified that no officer or sailor serving on board any warship or submarine has shown any symptoms or is suspected to be infected. It said all of them would be tested.

Navy sources said the 26 infected sailors — all of whom stayed at a single dormitory — had been isolated at INHS Asvini, the naval hospital at Colaba, Mumbai.

They said the sailor who tested positive on April 7 had been in touch with an ex-serviceman.

INS Angre has been put under lockdown and its residential block declared a containment zone.

“Stringent quarantine and safety protocols have been enforced for personnel and their families, with door-to-door screening being undertaken for identification of cases, if any,” the navy said.

INS Angre is adjacent to the naval dockyard at Mumbai where several frontline warships and submarines are docked. The Angre, seat of the Flag Officer Commanding-in-Chief of the Western Naval Command, houses naval barracks and sends supplies to the ships.

“The high number of positive cases has shocked the navy. The biggest concern is the prevention of an outbreak on a ship,” a defence ministry official said.

“The ships carry a large number of personnel in cramped spaces, and any positive case on board a ship can be disastrous as it can spread quickly.”

The navy had earlier issued a detailed Covid-19 advisory for its personnel saying whenever a suspected case was reported onboard at sea, the person must be isolated and all his close contacts quarantined. All effort should be made to evacuate him to an on-shore hospital.

Admiral Karambir Singh, the navy chief, had last week stressed the need to guard against Covid-19 outbreaks on board submarines and warships.

In a video message he had told personnel: “The danger posed by this disease is real, imminent and unprecedented.”

His message had come soon after American aircraft carrier USS Theodore Roosevelt reported 500 Covid-19 patients.

The severe onslaught of the coronavirus on the US navy, and the intense scrutiny on how the force has handled its spread, has led to the resignation of the acting navy secretary.

The USS Theodore Roosevelt, carrying more than 4,800 crew members, pulled into port on March 27.