(CNN) The United States will extend its set of social distancing guidelines until April 30, President Trump said in a coronavirus news briefing at the White House on Sunday.

"We will be extending our guidelines to April 30 to slow the spread," the President said. "On Tuesday, we will be finalizing these plans and providing a summary of our findings, supporting data and strategy to the American people."

As of Sunday evening there are more than 139,000 cases of coronavirus in the United States. At least 2,425 people have died.

Trump's administration issued guidelines on social distancing on March 16 aimed at containing the coronavirus outbreak

The guidance, which initially had a 15-day time frame, urged Americans to avoid groups of more than 10 and advised that older people stay home.

Trump hopes the country will be on its way to recovery by June 1, he said Sunday.

"A lot of great things will be happening," the President said.

Travel advisory issued for tri-state area

The Centers for Disease Control and Prevention issued the travel advisory Saturday, urging residents of the three states to "refrain from nonessential domestic travel for 14 days effective immediately." The states would have "full discretion" on implementing the advisory, which exempts employees in critical fields.

President Donald Trump had contemplated issuing an enforceable quarantine for parts of those states, then later said it will not be necessary.

"The fact of the matter is, people really aren't traveling a whole lot," New Jersey Gov. Phil Murphy said when asked about the advisory on ABC's "This Week" Sunday . "A travel warning, we're fine with."

Murphy added that his state is "all in on flattening the curve."

The CDC advisory came as some state officials began implementing their own restrictions on visitors from outside their states.

Florida is implementing its own strategies to slow the spread of the virus by setting up checkpoints for motorists entering the state, Gov. Ron DeSantis said Saturday.

According to a news release from the Florida Department of Transportation, travelers will be required to fill out a form with their travel history and contact information. Motorists coming from "areas with substantial community spread" including New York, New Jersey, Connecticut and Louisiana will be required to isolate themselves for 14 days, the news release said.

Gov. Greg Abbott of Texas expanded an executive order requiring people traveling to his state from certain places to be quarantined for 14 days.

The previous order mandated a quarantine for people flying into Texas from New York, New Jersey, Connecticut and New Orleans. The expanded version, announced Sunday, includes anyone driving into Texas from Louisiana, and anyone flying from the cities of Miami, Detroit, Chicago and Atlanta. It also includes Washington state and California.

Patients wait for coronavirus testing outside Elmhurst Hospital Center in New York on Friday.

US has the most cases worldwide

Sunday, Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases, a key member of the White House coronavirus task force, said on CNN's "State of the Union" that, based on modeling, 100,000 or more could die from the coronavirus in the United States.

Fauci reiterated that comment in that evening's White House briefing, telling reporters, "What we're trying to do is not to let that happen."

The United States surpassed China and Italy this week, becoming the country with the most confirmed cases worldwide. And the growing number of cases has also revealed new demographics facing severe illness.

Cases of young adults developing severe illnesses have been more widely reported, but children were thought to be avoiding the harshest effects.

On Saturday, state officials reported the death of an infant under age 1 who tested positive for coronavirus and is believed to be the youngest person to die of the virus in the United States.

An investigation is underway to determine the cause of death, the Illinois Department of Public Health said.

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Police and nurses are falling ill

Those charged with treating patients and maintaining order are feeling the effects of the pandemic as well.

A nurse for Jackson Health System in Miami, Araceli Buendia Ilagan, has died due to complications from the coronavirus, according to a Jackson Health spokeswoman. One colleague said the nurse, who worked in the intensive care unit, was "vital and irreplaceable."

Ilagan's death also has her colleagues worried about their own health and safety.

"Now everyone that works with her in the unit is scared that they may be carrying the virus as well," a nurse who worked closely with Ilagan told CNN.

Meanwhile, 12 nurses at the University of Illinois Hospital have tested positive for coronavirus, the state's nursing association said.

ln New York City, 730 uniformed NYPD officers and 96 civilian employees are infected with the coronavirus, according to a law enforcement official. Twenty-nine of them are hospitalized and one is in critical condition, the official said.

At least 4,662 officers -- about 12% of the department -- are out sick, either with the coronavirus or other ailments, the official said.

In a rare step, the NYPD is advising officers and employees with underlying conditions to seek permission from their commanding officers to work from home, the official said. Pregnant staff are being advised to do the same.

NYPD Commissioner Dermot Shea anticipates close to 900 NYPD employees will test positive for Covid-19 by Monday morning, he said in a news conference Sunday.

Cases are rising as first responders have dealt with a huge influx of emergency calls. FDNY Commissioner Daniel Nigro said Sunday the previous five days were the busiest in the department's history.

New York City's police department lost its first detective to Covid-19, marking the third death of an NYPD employee to the disease.

Gov. Cuomo paid homage to the detective, Cedric Dixon , in a news conference Sunday, along with Kious Kelly , an assistant nurse manager at New York City's Mt. Sinai Hospital who also lost his life.

Cuomo described what they and all first responders do as an "act of love and courage," driven by their "passion and belief in helping others."

"I don't even have the words to express my admiration for them," the governor said.

A push for medical supplies grows

Medical staff nationwide have struggled to maintain an adequate supply of personal protective equipment, hospital beds and ventilators.

Louisiana Gov. John Bel Edwards said a New Orleans convention center would be converted into an emergency hospital with a 1,000-bed capacity for coronavirus patients. The facility "will be open no later than a week from today," the governor said Sunday.

The shortage of personal protective equipment drove a group of New York nurses to protest outside the Jacobi Medical Center on Saturday, demanding the supplies they need to do their jobs safely.

"If we get sick, our patients will get sick. This is for our entire community," said Kelley Cabrera, a registered nurse. "If you look at what we are wearing in comparison to other countries, it's unacceptable."

The medical center said that although the staff has adequate supplies, there is a nationwide shortage and conservation measures are in place.

Trump approved four more emergency hospitals in New York. The facilities in Brooklyn, Queens, Staten Island and the Bronx will provide 4,000 beds.

Another 1,000 beds will be available this week in a temporary overflow hospital at Javits Convention Center in Manhattan, and an additional 1,000 beds will be on the USNS Comfort set to arrive in New York on Monday, Cuomo said.

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But officials believe the state will need 140,000 beds when it reaches the apex of the pandemic in 14 to 21 days, Cuomo said.

The administration will also facilitate the production or acquisition of "100,000 additional units" of ventilators over a 100-day period, Trump said.

Large corporations are also stepping up to feed the supply gap. New Balance announced Friday on Twitter that its US factories will work on developing, manufacturing and delivering facial masks to hospitals. The same day, Delta Air Lines announced it will fly medical professionals for free to areas significantly impacted by coronavirus.

And on Sunday, Trump announced that health insurers Humana and Cigna would be waiving co-pays, co-insurance and deductibles on coronavirus costs.