WASHINGTON (AP) — In response to rising COVID-19 infection numbers, the Smithsonian Institution is indefinitely shutting down operations at all its facilities, effective Monday and affecting seven museums, plus the National Zoo.

The Smithsonian said in a statement that its “top priority is to protect the health and safety of its visitors and staff.” No reopening date is scheduled.

The decision comes at a time of rising speculation over whether the District of Columbia will tighten virus restrictions in the face of a nationwide spike. Local figures, both for the number of new positive tests and the government’s preferred metric of a seven-day rolling average per 100,000, are at their highest point since May.

After shuttering all facilities in mid-March, the Smithsonian reopened the National Zoo on a limited basis on July 24, with all indoor buildings closed and timed entry passes to limit crowds. Since then, Smithsonian officials have gradually opened up other facilities, including the National Portrait Gallery and the Museum of African-American History and Culture.

The closure of the zoo's indoor facilities has meant that fans of the ever-popular pandas had to resort to webcams to get a glimpse of the new baby panda cub born to matriarch Mei Xiang in August.

"Due to the changing nature of the situation, we are not announcing a reopening date at this time," the Smithsonian said in its statement. “We will use this time to reassess, monitor and explore additional risk-mitigation measures.”

The nation’s capital is at the second phase of its reopening plan, which permits limited indoor seating in restaurants but requires all adults to wear masks outside their homes. Both Maryland and Virginia have recently boosted their restrictions, but D.C. Mayor Muriel Bowser said there were fewer rollbacks necessary in the city because it had consistently been more conservative that its neighbors.

“We have been very deliberate,” she said Wednesday. “We never had bars open. We never had spectators at sporting events.”

Bowser said her team is discussing more targeted “interventions” that they believe will have a tangible impact on the spread of the virus. She said those changes are coming soon.

Bowser has repeatedly warned about the dangers of small family gatherings such as birthday parties, and has appealed to her residents to skip the traditional Thanksgiving family meal this year. With the exception of Maryland and Virginia, which are exempted, residents of every state other than Hawaii and Vermont are currently required to receive a COVID-19 test before travelling to Washington.