(CNN) California public health officials are warning moviegoers who went to see "Avengers: Endgame" and other films at an Orange County movie theater last Thursday that they may have been exposed to measles by a woman in the audience.

The woman attended a midnight screening of the "Avengers" blockbuster at the AMC Dine-In Fullerton 20 on Thursday from 11 p.m. to 4 a.m, the Orange County Health Care Agency said.

Everyone who was in the building may have been exposed, not just at that particular screening room, the agency said.

The warning also applies to people who went to buildings at 5 Hutton Centre Drive in Santa Ana from last Wednesday through Friday.

The woman, who is in her 20s, reported having recently traveled to a country with widespread measles activity, the agency added.