NEW YORK (AP) — New York City is shuttering schools to try to stop the renewed spread of the coronavirus, Mayor Bill de Blasio said Wednesday in a painful about-face for one of the first big U.S. school systems to bring students back to classrooms this fall.

The nation’s largest public school system will halt in-person learning Thursday, sending more than 1 million children into all-online classes, the mayor said.

The Democrat said at an afternoon news conference that plans were being made to bring in-person learning back as quickly as possible if the infection rate drops, though he cautioned that the bar to return would be higher than it was to close down. He added that schools would definitely remain closed through Thanksgiving.

De Blasio said increased virus testing of children at schools would be a component of the return plan and parental consent for that testing would be required for pupils hoping to come back.

“We’re going to fight this back,” de Blasio said. “This is a setback, but it’s a setback we will overcome.”

It can’t be overcome soon enough for Darneice Foster. She has four children, ranging in age from 4 to 13, now set to be learning from home.

“I don’t know what I’m going to do, except pull my hair out,” she said.

The city’s springtime stretch of all-online learning was “really awful” for the family, which shares a one-bedroom apartment in Upper Manhattan, said Foster, a former pharmaceutical advertising worker who left her job some years ago when one of her children had health problems.

“Now, I really want my kids to catch up, and I’m one person,” she said. She said she would “look on the sunny side and just bear it for a few weeks,” hoping schools would reopen soon.

The city had said since summer that school buildings would close if 3% of all the coronavirus tests performed citywide over a seven-day period came back positive. As the rate neared that point last week, de Blasio advised parents to prepare for a possible shutdown.

The mayor said the rate equaled that mark as of Tuesday. And in fact, a revision of earlier city data showed it had likely been above that threshold since Nov. 11.

The city’s public school students will now be taught entirely online, as most already are. As of the end of October, only about 25% of students had attended class in person this fall, far fewer than officials had expected.

Some city parents and officials had lobbied hard for the mayor to take other actions first before restoring to a schools closure, like ending indoor restaurant dining or requiring nonessential businesses to close.

“It is a massive failure of leadership to have allowed our schools to close before we got a handle on the virus spreading in indoor restaurants, bars, and gyms, worship and other gatherings. Schools should be the last things to close, not the first,” City Council member Brad Lander said in a statement.

New York City’s school system, like others across the nation, initially halted in-person learning in mid-March as the virus spiked. In-person school resumed Sept. 21 for pre-kindergarteners and some special education students. Elementary schools opened Sept. 29 and high schools Oct. 1. To keep students spread out, the city offered in-person learning only part-time.