FLAGSTAFF, Ariz. — The federal agency that oversees schools that educate some Native Americans in nearly two dozen states issued an employee vaccine mandate Thursday.

The mandate covers faculty and staff at schools and dormitories operated directly by the U.S. Bureau of Education in states including Arizona, New Mexico and the Dakotas.

More than 180 schools operate under the agency’s umbrella, but about two-thirds are run by tribes under contract with the federal government or through grants, including on the Hopi reservation and most on the neighboring Navajo Nation.

The Bureau of Indian Education, which is part of the Interior Department, joins a growing number of government agencies that are requiring vaccinations or regular COVID-19 testing.

Interior Secretary Deb Haaland said bureau employees must be vaccinated no later than Oct. 15 and provide proof so the schools it operates can return fully to in-person instruction. Those who don’t comply could be fired or lose their contract, the Interior Department said.

“The department recognizes that education plays a critical role in promoting equity in learning and health, particularly for Indigenous communities that have been disproportionately affected by COVID-19,” the department said.

The schools will consider individual requests for exemptions but could require those who aren’t vaccinated to follow safety measures established by the U.S. Centers for Disease Control and Prevention, undergo regular COVID-19 testing and prove they’ve tested negative before they return in-person to schools or dormitories.

It’s unclear how many employees and schools are covered by the mandate. The Interior Department didn’t immediately respond to a request for that information Thursday.