After a long search, the location of the Navajo school was found thanks to Google Lens and that took some searching on Google Maps and Google Streetview.
It is indeed a school building and it's a high school and it was indeed in Kayenta, Arizona.
The shooting took place at Monument Valley High School.
The Navajo school is located on Mustang Boulevard and this is the address of the Navajo school:
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Mustang Blvd
Kayenta, AZ
86033
United States