On Thursday of last week, 42-year-old cinematographer Halyna Hutchins was shot and killed by actor Alec Baldwin after he fired a prop gun on the New Mexico set of the film Rust. Director Joel Souza, who was standing behind Hutchins, was also wounded but has since recovered.

Information about the incident has been slowly trickling out, but some details are fuzzy and others are unverified. It’s still unclear how the gun misfired, why it had potentially damaging projectiles in it, or what, exactly, Baldwin was doing when the gun went off.

Read more: Assistant director who gave Alec Baldwin gun had past safety concerns

Santa Fe County Sheriff Adan Mendoza and Santa Fe district attorney Mary Carmack-Altwies will hold a joint news conference on Wednesday to discuss the ongoing investigation into the shooting incident on the movie set. (You can watch live, top.)

According to court records, the gun Baldwin used was one of three that a firearms specialist, or armourer, had set on a cart outside the building where a scene was being rehearsed.

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Assistant director Dave Halls then allegedly grabbed a gun off a cart and handed it to Baldwin, indicating that the weapon was safe by yelling “cold gun,” court papers say. But it was loaded with live rounds, according to the records. Both the armourer and Halls have provided statements to the police.

Read more: Prop gun use on movie sets — What, exactly, is the protocol?

Baldwin, 63, who’s said to be incredibly distraught by the incident, described the killing as a “tragic accident.”

It remains an active, open investigation.

With files from The Associated Press