Los Angeles County will reimpose its mask mandate this weekend in the latest sign that public health officials are struggling with an alarming rise in coronavirus cases tied to the highly contagious Delta variant.

The county, home to 10 million people and the nation's second-largest city, Los Angeles, is one of several jurisdictions to recommend or mandate wearing masks or other pandemic restrictions in recent days as cases rise to worrisome levels in many parts of the United States. "We’re requiring masking for everyone while indoors at public settings & businesses, regardless of vaccination status so that we can stop the increased level of transmission we're seeing," the Los Angeles County Department of Public Health said on Twitter Thursday.

The mandate will begin on Saturday night at a minute before midnight, the agency said. The announcement follows six straight days in which more than 1,000 new COVID-19 cases have been reported in Los Angeles County, with nearly 400 people hospitalized with the coronavirus as of Wednesday, up 275 from the week before. Nine new COVID-19 deaths were reported on Wednesday alone.

Also on Thursday, Sacramento County in California recommended that masks be worn indoors even by people who are vaccinated. Austin, Texas, on Thursday urged people who are not vaccinated or otherwise high-risk of COVID-19 infections to avoid travel, indoor gatherings, dining out and shopping, and to wear masks. Earlier this week, Yolo County in California also recommended indoor masking, and in Springfield, Missouri, children and teachers have been required to wear masks during summer school.

“The drastic increase in cases is concerning – as is the number of people choosing not to get vaccinated,” Sacramento County Public Health Officer Olivia Kasirye said Thursday, announcing the new recommendations. Data from the U.S. Centers for Disease Control and Prevention show high levels of coronavirus transmission in numerous states, including Missouri, Mississippi, Florida, Nevada and Utah.

Across the country, health officials urged residents who have not yet done so to become vaccinated. Vaccines are approved and available for all people as young as 12 years old. “Our best protection against COVID-19 continues to be the vaccine," said Kasirye. "We urge all eligible residents to get vaccinated in order to protect themselves, and their family and friends.”