Mayor Eric Garcetti praised both the union and LAUSD administrators.
The principal said the school closed "to ensure the safety of our students, faculty and staff.” Native Americans say they have not threatened anyone.
Measles has been declared a public health emergency in one Washington county.
The Oscar-nominated performer interrupted her Las Vegas show over the weekend to send a message to the vice president and his wife on LGBTQ rights.
Lt. Jacob Portier also is accused of failing to report a war crime, destroying evidence and impeding the investigation of Special Operations Chief Edward Gallagher.