Gov. Kim Reynolds speaks during a COVID-19 news conference Thursday at the Iowa Capitol in Des Moines.

JOHNSTON — Gov. Kim Reynolds said Tuesday that she will require that people wear masks if they join indoor gatherings of 25 or more people as Iowa sees a surge of coronavirus infections that is threatening to overwhelm hospitals.

Reynolds said she signed a proclamation taking effect Wednesday that would require masks for indoor and outdoor gatherings of 100 or more people. The governor continued the requirement of 6 feet of distance between groups in bars and restaurants and limited groups to eight people unless they’re all members of the same household. She said the new rules don’t apply to school districts — nearly all of which already have the option of shifting to online-only learning because of the high positivity rate throughout the state.

Iowa Department of Education Director Ann Lebo said her department has approved for 24 school districts to move to some level of online instruction since Nov. 1 and is reviewing three more applications. The department approved a waiver Tuesday allowing online-only learning for Des Moines schools, the state’s largest district, but most of Iowa’s 330 public school districts are continuing to operate with at least some in-classroom instruction.

Asked why she didn’t impose a mask requirement for smaller gatherings, Reynolds said: “It’s a place to start and it’s progress from where we were.”

The mask requirements apply to social, community recreational leisure or sporting events, she said.

The Republican governor has repeatedly refused to impose a statewide mask mandate and was among the first governors nationally to remove most limits on gatherings that were imposed in the spring when the virus first began to surge. Noting the increasing number of people being treated for the virus in hospitals, Reynolds left open the possibility of new restrictions if infections don’t start declining.

The governor also said she was optimistic that an advertising campaign beginning this week would succeed in persuading people to wear masks and take other actions to reduce the spread of the virus, even though some county public health officials in rural areas have said many people don’t believe the virus is serious and inaccurately question the effectiveness of masks to prevent the virus’ spread.

“I’m here to tell Iowans I need your help. If you want to keep our businesses open, if you want to keep our kids in school, if you want to make sure we have hospitals and long-term care facilities and we have clinics that can treat not only COVID patients but can treat other individuals that have serious health conditions that need to go to the hospital then we all have to buckle down and take this serious,” she said.

Senate Democratic Leader Janet Petersen said Reynolds’ actions are like buying a smoke detector after your house is blazing out of control. House Democratic Leader Todd Prichard said the governor’s response is too little and too late.

“After ignoring the pandemic and public health guidelines for a month while campaigning, Gov. Reynolds has put the State of Iowa in a crisis today,” he said.

Separately the Iowa Supreme Court issued an order postponing jury trials until Feb. 1 unless the jury is sworn in by Nov. 16. Clerk of court offices remain open and nonjury trials and face-to-face court proceedings and services will continue. Chief Justice Susan Christensen said holding jury trials now “creates too high of a risk for someone to be exposed, even with the multitude of safeguards we have in place.”

On Tuesday, all but nine of Iowa’s 99 counties reported a 14-day positivity rate of 15% or more, a rate significantly above the level at which health experts recommend government measures to slow the spread of the virus that causes COVID-19.

The Iowa Department of Public Health reported 4,441 new confirmed cases in the past 24 hours, the fourth consecutive day new case counts surpassed 4,000. There were 27 additional deaths, raising the state total to 1,872.

Hospitalizations grew to 1,135 and new admissions to hospitals remained high at 166. There were 196 patients in intensive care units.

Hospital officials across the state are warning that the surge in cases is unsustainable and hospitals soon could be overwhelmed with patients.

The state reported 102 outbreaks in long-term care facilities, and at least three of the state’s prisons are experiencing outbreaks, with over 1,000 inmates and more than 100 state workers infected.

The seven-day rolling average of the positivity rate in Iowa has risen over the past two weeks to over 48%, according to researchers at Johns Hopkins University. The state’s rate is second only to South Dakota.