[tomschlick]

They didn't.

She was detained until the scene could be cleared. All those backup officers know when responding is that an officer called in a shooting and that there is a gun in the car. They detain her until they can get all of the information and then she is released so long as they are not pressing any type of charges against her.

[llamataboot]

She still hasn't been released. She's not under arrest. She's being interviewed as a witness to an officer involved shooting.

[tomschlick]

That seems within the law. If she is a direct witness to a fatal shooting there would be a critical need to get her side of the story as soon as possible, and usually that would be done by detectives at a police station, not the responding officers at a crime scene.

[ryanmarsh]

Source?

They can't take a statement on the street?