(Reuters) - Washington state officials urged patience on Wednesday as medical staff reported fear and anger among people told they could not be tested for the coronavirus due to limited capacity in a state facing the United States’ deadliest outbreak.

FILE PHOTO: Test tube with Corona virus name label is seen in this illustration taken on January 29, 2020. REUTERS/Dado Ruvic

Clinics in the Seattle area reported an increase in patients seeking tests as Washington reported 39 cases of coronavirus and 10 deaths.

Health officials and front-line medical staff in Seattle’s King County, the location of most cases, asked mildly sick people to stay home rather than inundate clinics and hospitals for tests and risk infecting others.

“We know there is huge demand out there for testing, we know there are a lot of people in our state who are sick and they want to know if they have Covid-19,” Washington State Health Officer Kathy Lofy told a news conference. “I want to tell you we are doing everything possible to expand testing capacity here in our state.”

Nurse practitioner Paula Ruedebusch asked patients not to take out frustrations on front-line medical staff.

“We have had patients presenting here, angry that they cannot be tested for COVID-19, yelling, cussing, throwing their dirty mask at us and even spitting their secretions on the floor and walls on their way out,” Ruedebusch, who works at an urgent care clinic in the Seattle suburb of Monroe, wrote on Facebook.

Testing was delayed after a first round of kits sent by the U.S. Centers for Disease Control and Prevention (CDC) failed and it took weeks for replacements to arrive in states.

The CDC initially set narrow criteria on who could be tested but widened them in the last day to anyone who has symptoms of Covid-19, Lofy said.

Washington still faces capacity issues, with the state public health laboratory only able to test around 100 people a day, Lofy said. The state hopes to ramp up testing through commercial labs.

Health officials are concerned that clinics and hospitals could be overwhelmed, said Patty Hayes, King County public health director.

“We do not want the situation that has been seen in other areas, in other countries where the healthcare system was overloaded, and unable to cope,” said Hayes.

To slow the virus’ spread, county officials recommended on Wednesday that residents avoid gatherings of more than 10 people and urged sick or elderly people to stay home.

Megan Farnsworth said patient volume was high at two Seattle-area walk-in clinics she directs, but not at record levels.

Much of her staff’s work is easing people’s fears and telling them to stay home and monitor their symptoms, she said.

“Honestly, patients are just scared and want someone in the healthcare field to tell them something that they can believe,” said Farnsworth, a doctor with Providence Regional Medical Center Everett.

Graphic - Tracking the novel coronavirus: here