London Mayor Sadiq Khan has declared a “major incident” as the virus's spread threatens to overwhelm the city's hospitals.

One in 30 Londoners now has COVID-19, the mayor said.

The city has 7,034 people currently hospitalized -- a 35% increase from the April peak.

The number of people in hospitals jumped by 27% from Dec. 30 to Jan. 6, Khan said.

The London Ambulance Service is now taking up to 8,000 calls per day, when an average day would bring 5,500 calls.

“The stark reality is that we will run out of beds for patients in the next couple of weeks unless the spread of the virus slows down drastically,” Khan said. “We are declaring a major incident because the threat this virus poses to our city is at crisis point. If we do not take immediate action now, our NHS could be overwhelmed and more people will die.”

Just as the U.S. hit its deadliest day since the start of the pandemic, Dr. Anthony Fauci, the nation's top infectious disease expert, told NPR that it may only get worse.

In an audio interview Thursday, Fauci was asked if we should expect the death toll to keep rising.

"I believe, unfortunately, that it will," he said. "As we get into the next couple of weeks in January, that likely will be a reflection of the holiday season travel and the congregate settings that usually take place socially during that period of time."

He added that because so many Americans chose to attend get-togethers during the holiday season, he and other experts believe "things will get worse as we get into January."

As of now, more than 360,000 Americans have died of COVID-19.

"Hopefully, if we really accelerate our public health measures during that period of time, we'll be able to blunt that acceleration," Fauci said. "But that's going to really require people concentrating very, very intensively on doing the kinds of public health measures that we talk about all the time. Now's not the time to pull back on this."

Because Los Angeles’ mortuary system is overwhelmed, the LA County Coroner is now beginning to step in and pick up bodies and store them until mortuaries can handle them.

This is so bodies don’t remain in personal homes and nursing homes for days waiting for a funeral home with space, officials said

“We will actually go out, pick up the person, bring them to our office, provide some safe and secure storage until the time the mortuary is able to take custody of their loved one,” Los Angeles County Coroner Chief of Operations Brian Elias told ABC News.

The coroner is adding a new temporary morgue next week made up of mainly refrigerated containers to help deal with the crush.  Before the pandemic, LA’s crypt could hold around 500 bodies.  They expanded that months ago to handle between 1000-1200. And next week it will expand that number again. Earlier this week, the LA County Coroner had about 750 bodies it was holding.

Every six seconds, someone is being diagnosed with COVID-19 and every eight minutes, someone is dying, LA Mayor Eric Garcetti told CNN Thursday.

“I am asking for folks across America, if you can spare a doctor or nurse, please were Americans, send it here,” Garcetti said.

-ABC News’ Alex Stone

There were at least 4,279 deaths recorded between 5 p.m. Wednesday and 5 p.m. Thursday, marking the first time the U.S. has surpassed 4,000 daily COVID deaths since the pandemic began, according to a count by ABC News.

In the first week of 2021, the U.S. reported more cases of COVID-19 than at any point in the pandemic so far, the second-highest number of deaths, and the most people hospitalized with the disease, according to the COVID Tracking Project.

In the U.S., more than 21.5 million people have been diagnosed with COVID-19, with at least 364,218 deaths.

The coronavirus pandemic has now killed more than 1.89 million people worldwide. Over 87.7 million people across the globe have been diagnosed with COVID-19, according to Johns Hopkins University.