As of Thursday afternoon, the United States remains the nation hardest hit by the pandemic, with a total of 18.6 million COVID-19 cases and roughly 329,000 relevant deaths reported nationwide, showed a tally by Johns Hopkins University.

Meanwhile, the remaining ICU capacity in the 11-county Southern California region and 12-county San Joaquin Valley region in Central California are still zero. The two regions are home to around 33 million people in the state, representing 84 percent of the state's population.

ICU capacity in the Bay Area, Greater Sacramento Region and Northern California region has dropped to 9.24 percent, 15.3 percent and 27.5 percent respectively.

Based on current ICU data, San Joaquin Valley, Southern California, Greater Sacramento and the Bay Area are under the regional stay-at-home order. Regions must remain lockdown for at least three weeks and will be eligible to exit the order only if ICU capacity projections for the following month are above or equal to 15 percent, according to the state's authorities.

"Today California hit a sobering milestone, we have surpassed 2 million COVID-19 cases. While this means we are leveraging our testing capacity, it is a reminder that this virus continues to spread through our communities," said Mark Ghaly, Secretary of California's Health and Human Services Agency in the release.

"Hospitals are full, ICU beds are few, people are dying. The simplest thing we can do, but also the most significant, is to stay home. We are the first line of defense against this virus and we must act now," Ghaly added.