WINDOW ROCK, Ariz. • The Navajo Nation is implementing a stricter weekend lockdown as it looks into new clusters of coronavirus cases from family gatherings and off-reservation travel.

Residents of the vast reservation that extends into New Mexico, Arizona and Utah will be required to stay home from Friday evening until early Monday morning. More recent weekend lockdowns were a day shorter.

Tribal President Jonathan Nez said public health experts and contact tracers are investigating new COVID-19 cases in the area served by Sage Memorial Hospital in Ganado, Arizona, and on the eastern side of the reservation in New Mexico. Nez said public health orders that restrict in-person gatherings, and that require social distancing and face masks weren’t observed.

A new public health order with more restrictive measures is expected Tuesday.

“It only takes a few positive cases to lead to another surge, and we all know that our health care system cannot handle another large surge,” Nez said in a statement. “We have to keep our guard up and hold each other accountable.”

The tribe reported 11 new cases of the coronavirus late Monday, which doesn’t include the new clusters. That brings the total number of cases to 10,131. The death toll stands at 548.

For most people, the new coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks.

But for some — especially older adults and people with existing health problems — it can cause more severe illness, including pneumonia, and death.