Image source, Getty ImagesImage caption, Santa Fe County Sheriff Adan Mendoza said the weapon used was functional
Investigators exploring a fatal shooting on a New Mexico film set say there was "some complacency" around safety.
Presenting their initial findings on Thursday's shooting, officials said they believe actor Alec Baldwin was handed a gun loaded with a live round.
The US actor then accidentally shot dead cinematographer Halyna Hutchins and wounded the film's director.
Prosecutors are refusing to rule out filing criminal charges over the case.
Santa Fe district attorney Mary Carmack-Altwies told reporters that "all options are on the table at this point" as their investigation continues.
Authorities said Wednesday they have recovered some 600 pieces of evidence so far - including three firearms and 500 rounds of ammunition.
Santa Fe County Sheriff, Adan Mendoza, said the ammunition trove constitutes "a mix of blanks, dummy rounds and what we are suspecting is live rounds" that require lab analysis.
He also said that a "lead projectile" was recovered from the shoulder of wounded director Joel Souza and handed over as evidence.
"I think the facts are clear - a weapon was handed to Mr Baldwin. The weapon is functional and fired a live round killing Ms Hutchins and injuring Mr Souza," he said about the killing.
The sheriff told reporters there were up to 100 people on the set of the Western film, called Rust, when the shooting happened.
He also confirmed that two other people had handled the gun before it was given to Mr Baldwin: the film's armorer Hannah Gutierrez Reed and assistant director Dave Halls.
Image source, Jim Weber/The New MexicanImage caption, Santa Fe County Sheriff's office say Actor Alec Baldwin is cooperating with the investigation
Court records say Mr Halls reportedly called out "cold gun" as he handed over the weapon, meaning it was considered safe. New details of his police interviews, reported by US media on Wednesday, say the assistant director has admitted to investigators that he did not check the gun's chamber for live rounds before handing it to Mr Baldwin.
New search warrant documents say armorer Ms Gutierrez Reed told investigators that live ammunition had not been kept on the film's set, with access to guns usually restricted to a few people with access to a safe.
Police identified the firearm shot by Mr Baldwin as an antique-edition F LLI Pietta Long Colt .45 revolver.
Investigators have also recovered a spent shell casing thought to be from the shooting incident.
Mr Baldwin, known for his work on US shows like 30 Rock and Saturday Night Live, is named as both an actor and producer on Rust. He is cooperating with investigators and has previously expressed his shock and sadness over what he described as a "tragic accident".
Last week's shooting death sparked debate about safety regulations on Hollywood sets and the use of "prop guns" on productions.
"Obviously I think the industry has had a record recently of being safe," Sheriff Mendoza told reporters. "I think there was some complacency on this set, and I think there are some safety issues that need to be addressed by the industry and possibly by the state of New Mexico."