(Reuters) – About half a dozen states including Texas and Arizona are grappling with a rising number of coronavirus patients filling hospital beds, fanning concerns that the reopening of the U.S. economy may spark a second wave of infections.

The rally in global stocks came crashing down on Thursday over worries of a pandemic resurgence. The last time the S&P 500 and Dow fell as much in one day was in March, when U.S. coronavirus cases began surging.

A recent spike in cases in about a dozen states partially reflects increased testing. But many of those states are also seeing rising hospitalizations and some are beginning to run short on intensive care unit (ICU) beds.

Texas has seen record hospitalizations for three days in a row, and in North Carolina only 13% of the state’s ICU beds are available due to severe COVID-19 cases. Houston’s mayor said the city was ready to turn its NFL stadium into a make-shift hospital if necessary.

Arizona has seen a record number of hospitalizations at 1,291. The state health director told hospitals this week to activate emergency plans and increase ICU capacity. About three-quarters of the state’s ICU beds are filled, according to the state website here

“You’re really crossing a threshold in Arizona,” said Jared Baeten, an epidemiologist at the University of Washington. “The alarming thing would be if the numbers start to rise in places that have clearly already peaked and are on their downtrend,” he said, referring to New York and other Northeastern states where new cases and deaths have plummeted.

Health experts worry there could be a further rise in infections from nationwide protests over racial injustice and police brutality that packed people together starting two weeks ago.

STATES WITH RISING CASES

Arizona, Utah and New Mexico all posted rises in new cases of 40% or higher for the week ended June 7, compared with the prior seven days, according to a Reuters analysis. New cases rose in Florida, Arkansas, South Carolina and North Carolina by more than 30% in the past week.

(Open tmsnrt.rs/2WTOZDR in an external browser for a Reuters interactive)

Dr. Anthony Fauci, the top U.S. infectious disease official, told Canada’s CBC news that more cases are inevitable as restrictions are lifted.

“We also as a whole have been going down with cases,” Fauci said. “But I think what you mentioned about some states now having an increase in the number of cases makes one pause and be a little bit concerned.”

Even if hospitals are not overwhelmed by coronavirus cases, more hospitalizations mean more deaths in the coming weeks and months, said Spencer Fox, research associate at the University of Texas at Austin.

“We are starting to see very worrying signs about the course the pandemic is taking in cities and states in the U.S. and around the world,” he said. “When you start seeing those signs, you need to act fairly quickly.”

Total U.S. coronavirus deaths are now over 113,000, by far the most in the world. That figure could exceed 200,000 at some point in September, Ashish Jha, the head of Harvard’s Global Health Institute, told CNN.

Jha said the United States was the only major country to reopen without getting its case growth to a controlled level – defined as a rate of people testing positive for the coronavirus remaining at 5% or lower for at least 14 days. Nationally, that figure has been between 4% and 7% in recent weeks, according to a Reuters analysis.

Health officials have stressed that wearing masks in public and keeping physically apart can greatly reduce transmissions, but many states have not required masks.

“I want the reopening to be successful,” Harris County Judge Lina Hidalgo, the top executive for the county that encompasses Houston, told reporters. “But I’m growing increasingly concerned that we may be approaching the precipice of a disaster.”