The 10th floor in the Port of Long Beach’s Downtown office building has been closed for cleaning after an employee tested positive for coronavirus, the Post has learned.

The Port building sits in the new Long Beach Civic Center across from City Hall. Employees who work on the building’s 10th floor were told via email on Tuesday night to work from home because the floor would be closed for cleaning, according to multiple sources.

The floor houses the Port’s communications, business development and government relations departments and includes some employees who have also worked in the city’s Joint Communications Center, an emergency communications hub for coronavirus information.

Port of Long Beach Executive Director Mario Cordero said in a statement that the employee who tested positive hasn’t been to any Port facility since mid-march.

“The person is self-quarantined at home, and is recovering from symptoms,” he said. “The exposure, according to the Long Beach Health and Human Services Department investigation, is not thought to have occurred in the workplace.”

Cargo continues to flow through the Port, according to Cordero, and the closure hasn’t significantly affected trade operations.

“Employees from the closed floor were mostly telecommuting before today, and now have all been assigned to telecommute for the time being,” he said. “Port offices have been closed to the public, along with the rest of the Civic Center, since March 16.”

Health officials on Tuesday reported there were 123 confirmed COVID-19 in Long Beach, although the true number is almost certainly higher because testing has been limited. As a whole, Los Angeles County reported 548 new cases Tuesday for a total of 3,011. Across the county, 54 people have died from COVID-19 as of Tuesday.

One person has died from the coronavirus in Long Beach, and about 20% of patients have required hospitalization of some kind, according to the city.