OLYMPIA – Public and private schools in King, Snohomish and Pierce counties will be closed starting no later than next Tuesday and won’t reopen until after April 24.

Gov. Jay Inslee and school officials announced the closures, which will affect 43 school districts in the state’s most populous counties, as a way to contain the spread of COVID-19.

“Our state has been taking bold and aggressive action against COVID-19,” Inslee said. “Today we take another such act.”

At this point, that action doesn’t apply to any districts in Spokane County.

But Inslee said the closures could be extended to the rest of the state as the virus spreads, although it won’t necessarily be based on a certain level of exposure or number of cases.

“This is going to be a judgment call,” he said.

Those judgments could be exercised at the local level, according to Shelley Redinger, superintendent of Spokane Public Schools.

Asked Thursday about criteria for school closure, Redinger said “there is no set number” and that the district will make its decisions in partnership with the Spokane Regional Health District.

Districts in the three affected counties are being asked to set up a system to provide lunches at schools or to deliver box lunches, although delivery of those lunches might ultimately involve the National Guard.

Schools might also provide child care with proper social distancing rules, following rules of hand-washing and sanitizing surfaces, and making sure children stay home if they’re sick.

All school districts in the state should expect to develop plans for a possible closure, he said.

“We need our districts across the state to be ready,” he said. “Start thinking about it.”

Spokane Public Schools has been doing that for at least two weeks, Redinger said Thursday.

“We feel like we have good plans in place,” Redinger said. “We are monitoring the situation and meeting daily.”

Redinger also said that the district has plans to provide child care and to address nutritional needs for students from low-income families.

“That’s something we’ve been working on,” said Redinger, who added that details are still being finalized.

Should buildings close and lessons go online, Redinger said the district is working to provide better access to computers, hot spots and connections.

“That’s a real concern, and we have a number of different plans,” Redinger said.

Effective immediately, per state and local government guidance, the district is restricting in-building, school-related activities involving groups larger than 250 people.

“We are taking measures toward social distancing by not mixing people outside our school community,” the district said in a letter to families.

“The safety and education of our students will continue to be our focus moving forward,” the letter continued.

Superintendent of Public Instruction Chris Reykdal said children have been safe at schools, and the infection rate for young people is very low. But they can be carriers of the virus, even if not symptomatic, and put parents and grandparents at risk, he said.

The closures announced Thursday will affect about 600,000 students or about half of those in the state, Reykdal said. Schools in the three counties are seeing a large increase in the number of student absences.

On Wednesday, Inslee announced that gatherings of more than 250 people in those three counties, the state’s three most populous, will be canceled or postponed

That emergency order covers concerts, religious services, festivals and athletic contests in King, Snohomish and Pierce counties. Inslee said it was “highly likely” the order will be extended beyond March, and could be extended to other areas of the state if the COVID-19 virus spreads.