All Marion County public schools will close until April 6 to reduce the risk of spreading of the novel coronavirus, Indianapolis Mayor Joe Hogsett announced at a press conference Thursday.

The closures come after a second case of COVID-19 was found in Indianapolis on Wednesday evening, said Marion County Public Health Department director Virginia Caine. The second case is an adult, she said, not a student. She declined to give more information at this time.

“We have not come to this decision lightly,” Caine said. “We believe it is in the best interest of our children and our community as a whole. This is a time for students to stay home and not venture into public spaces.”

The closures will affect more than 150,000 students in Indianapolis districts and charter schools. All Marion County schools will close by Monday; some districts, including Indianapolis Public Schools, will close starting Friday.

It is not clear yet if schools will provide online learning for students or provide food to students who typically rely on meals provided at schools. Many public schools were already scheduled to take spring break in the coming weeks.

The closures were a conservative step compared to some other larger districts around the country, including New York City and Chicago, which have more confirmed cases of the illness but reiterated commitments to stay open. But two states, Ohio and Maryland, decided Thursday to shut down all K-12 schools in attempts to contain the spread of the coronavirus.

Indianapolis schools will release more detailed plans following Thursday’s announcement, officials said. Schools will be allowed to waive up to 20 days of missed classes, per new guidance from Gov. Eric Holcomb released Thursday.

Indiana students in grades 3-8 are expected to take ILEARN between April 20 and May 15 — soon after some are expected to return from several weeks off of school as a result of the coronavirus closures. But that could change: The U.S. Department of Education announced Thursday that it will consider waiving requirements for statewide tests.

The state exams are already expected to be relatively low stakes because lawmakers approved a “hold-harmless” measure last month that protects schools and teachers from negative consequences from low test scores on the new assessment for two years.

The 11 Marion County school districts include Indianapolis Public Schools, Beech Grove, Speedway, Wayne Township, Washington Township, Pike Township, Perry Township, Franklin Township, Lawrence Township, Warren Township, and Decatur Township. The city also has dozens of independently managed public charter schools.

“To those who argue these policies will be disruptive, my answer is simple: They better be. This virus and the threat it poses to our city, our state, is massive,” Hogsett said. “These things won’t be easy. And there are unfortunately more difficult days ahead. But I am confident that we are up to the challenge.”

Read the latest on Indiana school closures here.