Ohio Department of Health Director Amy Acton said at a press conference alongside Gov. Mike DeWine (R) that given that the virus is spreading in the community in Ohio, she estimates at least 1 percent of the population in the state has the virus.

"We know now, just the fact of community spread, says that at least 1 percent, at the very least, 1 percent of our population is carrying this virus in Ohio today," Acton said. "We have 11.7 million people. So the math is over 100,000. So that just gives you a sense of how this virus spreads and is spreading quickly."

She added that the slow rollout of testing means the state does not have good verified numbers to know for sure.

"Our delay in being able to test has delayed our understanding of the spread of this," Acton said.

The Trump administration has come under intense criticism for the slow rollout of tests. Dr. Anthony Fauci, a top National Institutes of Health official, acknowledged earlier Thursday it is "a failing" that people cannot easily get tested for coronavirus in the United States.

Not everyone with the virus has symptoms, and about 80 percent of people with the virus do not end up needing hospitalization, experts say. However, the virus can be deadly especially for older people and those with underlying health conditions.

The possible numbers in Ohio are a stark illustration of how many cases could be in other states as well, but have not been revealed given the lack of widespread testing.

More than 1,300 people in the U.S. have currently tested positive for the illness, according to data from Johns Hopkins University, while about three dozen people in the country have died.

Vice President Pence, who is overseeing the administration's coronavirus response, said earlier Thursday that the U.S. can expect "thousands of more cases."

Ohio officials said they are taking major actions to try to slow the spread of the virus. They are closing schools in the state for three weeks and banning large gatherings of 100 or more people.

The state currently has just five confirmed positive cases, and 30 negative tests. Acton said Thursday that it appears that the number of cases of the virus doubles every six days.

As other experts have as well, she urged actions to slow the spread of the virus to avoid overwhelming the capacity of hospitals. Banning large gatherings and stopping school is part of that process.

"We're all sort of waking up to our new reality," she said, adding later that the state is "in a crisis situation."

Noting the concerns about hospital capacity if the number of cases spikes too quickly, Acton said "there are only so many ventilators," referring to machines that allow people to breathe when they cannot on their own.

Models indicate the number of cases could peak in late April to mid-May, she said.

If people are not seriously ill, she urged them to stay home so that only the sickest people who most need help are showing up at hospitals.

"This will be the thing this generation remembers," she added.