Visitors approach the Bunker Hill Monument, Monday, Dec. 24, 2018, in Boston. Credit: Steven Senne | AP

BOSTON — Schools in Massachusetts will close for at least three weeks, and all gatherings of more than 25 people will be banned in the latest attempt to arrest the spread of the coronavirus, Gov. Charlie Baker announced Sunday.

The governor also ordered all dine-in restaurants to close for a month. Take-away and delivery services won’t be affected by the rules, nor will grocery stores or pharmacies.

“I realize these measures are unprecedented,” Baker, a Republican, said at a news conference announcing the directives. “But we’re asking our residents to take a deep breath and understand the rationale behind this guidance.”

On Sunday, the state reported it has 164 cases of COVID-19, the illness caused by the virus. That was an increase of 26 over the day before.

Of the cases, 108 were associated with a meeting of executives of the firm Biogen at a Boston hotel last month.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia, or death. The vast majority of people recover.