The US National Guard has been deployed to three states to fight coronavirus as millions face stay at home orders

President Donald Trump speaks during a coronavirus task force briefing at the White House, Sunday, March 22, 2020, in Washington. (AP Photo/Patrick Semansky) (Patrick Semansky, Copyright 2020 The Associated Press. All rights reserved.)

(CNN) -- As US coronavirus cases top 34,000, the federal government has activated the US National Guard in three of the hardest hit states -- California, Washington and New York.

Nearly half all US cases -- 16,887-- are in New York state, making it the epicenter of the US outbreak. New Yorkers, along with millions of people in at least seven other states, are facing orders from their governors aimed at keeping them home to prevent further spread.

There are 34,354 cases of coronavirus across the US. Covid-19, the disease caused by coronavirus, has killed at least 414 people across all 50 states, the District of Columbia, Guam, Puerto Rico and the US Virgin Islands.

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President Donald Trump said Sunday that the federal government was deploying National Guard units to the three hardest hit states “to carry out approved missions” and as a “backup” to state leaders. Governors will remain in command, Trump said.

The deployment comes as more than 100 million people in at least eight states face orders from their governors to stay home to curb the spread of the virus.

Stay at home orders

California, Illinois, New York and New Jersey were already under stay at home orders over the weekend. Ohio, Louisiana and Connecticut will join them on Monday. An order goes into effect on Tuesday in Delaware.

The orders encourage social distancing measures but make exceptions for people to leave their homes for things like buying food, picking up medicine and going to work for essential jobs. Some encourage being outside and active -- as long as it isn’t done in groups.

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Breaking the order could result in a fine in New York and Connecticut.

“These are not helpful hints. ... There will be a civil fine and mandatory closure for any business that is not in compliance” starting Sunday, New York Gov. Andrew Cuomo said.

‘All in on the medical supply front’

The orders are intended, in part, to reduce stress on the health care system.

High demand for medical equipment has forced states to compete with one another as they struggle to get what they need to treat their patients, Cuomo said Sunday.

"In some ways, we're savaging other states. I'm trying to buy masks. I'm competing with California and Illinois and Florida," he said.

On Monday, Sens. Chris Murphy of Connecticut and Brian Schatz of Hawaii are introducing a bill to require the President to fully use the Defense Production Act to ensure the necessary supply of medical equipment.

The 1950 law gives the president the ability to force factories to produce key equipment and allocate resources where they are needed. President Trump invoked the bill last week but said he does not plan to use it.

The bill would require the President to ensure the production of at least 500 million N95 respirators, 200,000 ventilators, 20 million face shields, 500 million pairs of medical gloves and 20 million surgical gowns.

"Anything that can provide relief to the frontline troops, do it. I would go all in right now. All in," Sen. Lindsey Graham, a South Carolina Republican and one of Trump's close allies, said. "Be all in on the medical supply front."

On Sunday, Trump approved a disaster declaration for California that will bring supplies, medical stations and naval hospital ships to the state, he said at a briefing. Similar declarations were previously issued for New York and Washington state.

More testing through constraints

The number of US coronavirus cases has surged as tests have become easier to access.

About 254,000 Americans have been tested, Vice President Mike Pence told reporters Sunday. That total does not include local hospitals or local health care labs, the vice president said.

But increasing testing has put pressure on dwindling medical supplies and increased the possibility of exposure, and authorities in some places have made the choice to test only high-risk patients or patients in cases in which results would significantly change the course of treatment.

Despite the constraints, coronavirus testing resources are being set up across the country. The city of Los Angeles is implementing a new web portal that would direct those who might be in the highest risk criteria to a testing center. In Chicago, two Walmart center parking lots are being designated as drive-through testing sites. And a new drive-up testing facility in Miami will give health care workers and first responders priority testing, Florida Gov. Ron DeSantis said.

Outbreaks among the vulnerable in nursing homes

Nursing homes have seen spikes in cases of the virus, which health officials say is more likely to cause serious illness in older people and those with underlying health conditions.

Seven nursing homes across Arkansas have reported cases, with 41 linked to Briarwood Nursing Home in Little Rock, according to Arkansas Department of Health Secretary Dr. Nate Smith. Residents accounted for 35 cases and staff members for six, Smith said during a Sunday news conference.

At the assisted living facility Atria Willow Wood in Broward County, Florida, the virus has resulted in three deaths and seven additional positive cases with the results pending for five other residents, a statement from Senior Vice President of Care Mike Gentry said.

DeSantis said the facility did not take precautions against the virus, allowing staff who hadn't been screened for symptoms to freely enter the building. But Atria said the governor's comments do not accurately reflect its practices.

At least seven deaths and 24 confirmed cases are linked to Lambeth House, a retirement community in New Orleans, according to Dr. Alexander Billioux, the assistant secretary of health for the state's Office of Public Health. Seven other facilities in the state have reported cases, he said.

The first known nursing home outbreak was at the Life Care Center in Kirkland, Washington. The center is associated with 35 deaths in one of the hardest hit states, the county health department said.

CORRECTION: This story has been updated to correct the number of people facing stay-at-home orders across the US.