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.