SEATTLE—Thirty thousand Boeing employees must start taking vacation or sick time, or apply for unemployment, after the airplane maker decided to keep its Puget Sound plants closed indefinitely.

The workers had been paid during the initial two-week work stoppage that began March 25, when Boeing closed its local factories to grapple with the spread of COVID-19, the disease caused by the coronavirus.

In an April 4 email, the company told employees it “is extending the temporary suspension of operations at all Puget Sound area and Moses Lake sites until further notice.”

Boeing has roughly 70,000 employees in the state. The decision affects about 30,000 of them, mostly production workers. Other employees who can work from home will continue to do so, and volunteer employees will continue to maintain essential services at the plants.

Boeing’s decision comes as Washington state continues to report increasing numbers of coronavirus cases, though at a slower rate than some other areas of the country. On April 4, state Department of Health officials confirmed an additional 393 cases and 28 deaths from COVID-19, bringing the state total to 7,984 cases and 338 fatalities. The bulk of the cases remain in King County, where 3,158 people have fallen ill and 208 have died.

Boeing said its decision was based on its “continuing focus on the health and safety of its employees, current assessment of the spread of COVID-19 in the state, the reliability of the supply chain, and additional recommendations from government health authorities.”