PARIS (AP) — The French aircraft carrier Charles de Gaulle headed back to port Wednesday due to a possible virus on-board outbreak of the new coronavirus, France's Defense Ministry said.

The Defense Ministry said in a statement that around 40 sailors showed symptoms compatible with COVID-19, the disease the virus causes.

“They have been placed in isolated confinement out of precaution.” French government spokeswoman Sibeth Ndiaye said.

A similar outbreak on the USS Theodore Roosevelt led to the firing of its captain last week and the resignation Tuesday of the acting U.S. Navy secretary.

A medical team equipped with test kits was set to board the Charles de Gaulle to confirm whether any crew members were infected and if so, to prevent the virus from spreading further, the ministry said.

Gatherings on the ship have been limited and sanitary practices reinforced, including the disinfecting of shared spaces, phones and computers after every use.

The aircraft carrier, which was on a mission in the Atlantic Ocean, is returning immediately to its base in the port of Toulon, on the Mediterranean coast, where it was originally expected to dock April 23. More than 1,700 crew members are on the French naval vessel.

The U.S. Navy said at least 230 crew members of the USS Theodore Roosevelt tested positive as of Tuesday.