NEW YORK — New York City's coronavirus test results have not reached the level that would trigger a shutdown of public school buildings, so schools will remain open for now, Mayor Bill de Blasio announced Sunday.

"Thankfully, schools will remain open on Monday, but we have to keep fighting back with everything we've got," de Blasio said on Twitter.

De Blasio had warned Friday that schools could close as soon as Monday if the city crossed the threshold set earlier of 3% of coronavirus tests citywide coming back positive over a seven-day period. The rate stayed short of that on Sunday, at 2.57%, he said. 

New York City's public school system, by far the nation's largest with more than a million students, was one of few big-city districts to reopen classrooms this fall after the pandemic forced schools across the United States online in the spring. 

Parents were given a choice of all-remote instruction or a "blended learning" system with students in class some days and learning online the other days.

About 280,000 students have attended in person, fewer than city officials had expected.

New York City has the nation's largest public school system. It became one of few big-city systems to reopen classrooms this fall after the pandemic forced schools online in the spring. 

Families of New York's more than 1 million students could choose to stick with all-remote learning for the fall, or to try a new "hybrid" plan involving some days in school and others on-screen.

About 280,000 students have attended in person, far fewer than the city originally expected.