Mortuaries in New Orleans are out of space, and the mayor said she needs help getting more refrigeration.
New York, New Jersey and Detroit will see peaks in hospitalizations and deaths this week, the US Health and Human Services assistant secretary said.
Such peaks will happen in other US cities in the coming weeks, Dr. Brett Giroir told NBC's "Today" show Monday.
He said peaks reflect infections that occurred two or three weeks ago.
"We may be seeing the worst upon us right now in terms of outcomes," Giroir said.
But there may be many more deaths from coronavirus than we realize, the US Centers for Disease Control and Prevention said. Some "may be misclassified as pneumonia deaths in the absence of positive test results," the CDC said.
"We really are just seeing the tip of the iceberg, and a lot of it has to do with the tests we have available," said Dr. Panagis Galiatsatos, a pulmonary and critical care physician at Johns Hopkins Medicine in Baltimore.
US Surgeon General Dr. Jerome Adams described the week ahead as a "Pearl Harbor moment" and a "9/11 moment." He told "Fox News Sunday" that this week will be the "hardest and the saddest" week many Americans have ever faced.
What hotspots across the country are grappling with
In New Orleans, the coroner's office and mortuaries have reached their limits, Mayor LaToya Cantrell said. She's asked the federal government for additional refrigeration.
The New Orleans convention center, which sheltered Hurricane Katrina evacuees 15 years ago, has now been converted into an emergency hospital. It's set to open Monday.
Across Louisiana, more than 13,000 people have been infected with coronavirus and at least 477 have died. Gov. John Bel Edwards said his state could run out of ventilators by the end of the week if cases continue to surge.
But the hardest-hit state, New York, reported a bit of good news. On Sunday, New York Gov. Andrew Cuomo reported a drop in the daily number of reported deaths for the first time in days.
He also said ICU admissions and daily intubations were down and the hospital discharge rate was "way up."
But Cuomo warned it's still too soon to tell if the trend will hold. He said New York may be approaching its peak in cases.
Religious holidays threaten social distancing
Health officials are stressing the need for social distancing as several faiths observe religious holidays.
This week is Holy Week in the Christian faith, culminating with Easter on Sunday. The Jewish holiday of Passover starts Wednesday evening. And the Muslim holy month of Ramadan begins later this month.
Boston Mayor Marty Walsh said he empathized with worshipers but implored them to stay home.
"I know it's a very difficult thing, as a Catholic," Walsh said.
"We don't get our rights to worship freely from the government. We get those from God," Spell said Sunday. "We'd rather obey God than man."
Many places of worship are holding services virtually to help mitigate the spread of coronavirus.
Miami-Dade County Mayor Carlos Gimenez thanked religious leaders who held services online, calling it the "safest way to keep us all connected."
Scrambling for solutions
With no end to this pandemic in sight, more Americans are getting creative in helping fight the virus's spread.
The Department of Veterans Affairs will open more than 1,500 hospital beds for civilians in multiple states, VA Secretary Robert Wilkie said.
The VA is helping in New York, New Jersey, Louisiana, Michigan and Massachusetts.
Doctors and nurses say any help is needed.
In one Brooklyn emergency room, it seems almost every patient -- no matter what they came in for -- is found to have coronavirus, Dr. Sneha Topgi said.
"I think we're still at the beginning, and I am scared," Topgi said. "I'm scared for myself, and I'm scared for everyone in general."