First there was the state of emergency declaration canceling large gatherings. Then came public school closures, followed by bars, restaurants, movie theaters and other public spaces.

But there's one tool Gov. Tim Walz says he's not ready to use to prevent the spread of the new coronavirus in Minnesota — at least not yet.

The DFL governor said it's not time to issue a "shelter in place" order, a dramatic measure already being deployed across all of California and being considered in New York City. It's an extreme form of social distancing, slowing the virus by confining people to their homes except for essential business.

"I think what I would say to Minnesotans is: That toolbox that I told you I would open last Friday … that is one of them in there," Walz said. "Last Friday we didn't think there would be any need to close schools. Last Saturday we didn't think there would be any need to close bars. So that's the speed of this."

Walz said he's been in communication with the Minnesota National Guard about its role, but so far it hasn't been deployed for response to COVID-19.

"Currently the Minnesota National Guard does not have imminent tasks related to prevention or response, but is in constant communication with the governor's staff and state agencies should we be needed for future support," said Maj. Gen. Jon Jensen, Minnesota National Guard adjutant general.

If deployed, a shelter in place order would be the state's most drastic move yet against the virus. The actions taken until now have already disrupted Minnesotans' normal way of life, crippling businesses and idling tens of thousands of workers. Nevertheless, by Thursday Minnesota reached 89 cases of COVID-19, the illness caused by the virus, and public health officials said they believe it is being spread by residents in every corner of the state.

Ryan Demmer, an associate professor in the epidemiology and community health division of the University of Minnesota's School of Public Health, said there's never been a widespread shutdown of U.S. public life during a pandemic, but extreme social distancing efforts in places like China went a long way in slowing the number of infections.

"In the short run it's one of our only tools. Staying away from people is going to be very powerful," he said. "Social distancing, we know, is important and we should keep our options open moving forward with our eyes wide open and learn from experiences in other places. We should be watching what's happening in San Francisco right now."

Similar lockdowns have taken place in other countries, including Italy, Spain, France and China.

Officials from Portland, Ore., to Boston are saying such a mandate could be needed in the future. New York City Mayor Bill de Blasio recently told residents to prepare for an order, but Gov. Andrew Cuomo, who would need to approve it, has rejected the idea. Similarly, Washington Gov. Jay Inslee has said it's not time for a shelter in place order, despite the urging of some. The Seattle area was the epicenter of the initial U.S. outbreak.

In California, shelter in place orders were first issued in northern counties and asked millions of residents to stay in their homes except for "essential needs" like grocery shopping, exercise and care for family members. Certain employees, such as health care and government workers, are also allowed to go to their jobs. But gatherings are barred, and law enforcement is asked to step in and enforce the order if necessary. So far, that's meant minor fines for people or businesses who are not in compliance.

Thursday night, California's governor asked the entire state to follow suit.

In Minnesota, an edict to stay home would likely face intense scrutiny from Senate Republicans, some of whom have already questioned Walz's authority to shutter bars and restaurants and change unemployment rules.

"While we understand the necessity of Governor Walz to lead in this time of crisis, that leadership should not be unilateral and unchecked," said Senate Majority Leader Paul Gazelka, R-East Gull Lake.

But DFL Attorney General Keith Ellison said the governor is well within his powers under state law to protect Minnesotans.

"My office and I are working closely with the governor and state agencies to ensure that every executive order during this peacetime emergency has a solid legal and constitutional basis," Ellison said.

Staff writers Stephen Montemayor, Jessie Van Berkel and Torey Van Oot contributed to this report.