Boston Mayor Marty Walsh reversed course Friday night and said Boston Public Schools will be closed for six weeks beginning Tuesday, after announcing earlier in the day that schools would be open.

While there have been no new coronavirus cases in the schools, Walsh said, “We are not going to wait for more cases to be confirmed. . . . Starting Tuesday we are closing Boston Public Schools to all students.”

Walsh said the plan is to reopen the schools April 27, after the schools’ previously planned Easter week break. He said it is possible the schools will reopen earlier. The schools will be open Monday in order to give families more time to prepare for the shutdown.

Walsh’s announcement followed a rolling string of announcements from other schools and districts in the area that they are closing to prevent the spread of coronavirus, including Boston’s Catholic schools.

Thomas Carroll, superintendent of schools of the Roman Catholic Archdiocese of Boston announced Friday that "all Archdiocese of Boston parish schools and Archdiocesan elementary and high schools will be closed for two weeks from Monday, March 16 through Friday, March 27. On an ongoing basis, we will consider whether this period needs to be extended further,"

Walsh said Friday evening he suspects other districts will have to extend their closures for longer than the two weeks most have announced.

At a press briefing Friday morning to announce the delay of this year's Boston Marathon, Walsh said "there will be school Monday; there will be school next week."

Other schools across the region have already announced closures. Arlington, Bedford, Belmont Burlington, Lexington and Winchester schools announced in unison that they will close for two weeks, and Everett schools have announced a 30-day closure.

Some Boston Public School parents and activists had started a petition to urge Walsh to close the schools to prevent transmission of the virus, and nearly two dozen municipal leaders have urged Gov. Charlie Baker to close schools statewide.

But Baker said at a press event later in the day that he is not ordering schools to close because public health officials have concluded "just shutting schools down completely does not appear to be the appropriate thing to do at this time." Baker said schools can be closed on a case-by-case basis depending on the emergence of an outbreak in a community or other factors.

Walsh met with several Boston city councilors late Friday, after which councilor Michelle Wu tweeted “In our conversation, Mayor Walsh confirmed that Boston Public Schools will inevitably be closed—the City is working on a plan to balance the safety & needs of our kids & school community, & that plan will be announced in the next 24 hours.”

Walsh said he is planning a press conference Sunday to lay out more detailed plans for providing food and educational materials to students while the schools remain closed.