The Santa Fe County Sheriff said Wednesday that other live rounds may have been on the set of “Rust” last week, in addition to the one that killed cinematographer Halyna Hutchins and wounded director Joel Souza.

Sheriff Adan Mendoza said that investigators recovered 500 rounds of ammunition, which included a mix of blanks, dummy rounds and, possibly, live rounds. The sheriff said that investigators are continuing to interview witnesses in an effort to determine how live rounds made it onto the set.

“We’re going to determine how those got there, why they were there, because they shouldn’t have been there,” Mendoza said.

Hutchins was shot during rehearsal of a scene at the Bonanza Creek Ranch, a popular filming location near Santa Fe. Alec Baldwin, the star of the film and also a producer, was holding the gun at the time, and was demonstrating how he would point it toward the camera when it went off. According to affidavits in the case, Baldwin had been told he was holding a “cold gun,” and was unaware it contained a live round.

Mary Carmack-Altwies, the local district attorney, said it is too soon to say whether any charges will be filed.

“We can’t say it was negligence by whom, how many people were involved,” Carmack-Altwies said. “It is a very complex case… If the facts and the evidence and law support charges, then I will initiate prosecution at that time. I am a prosecutor that was elected in part because I do not make rash decisions and I do not rush to judgment.”

Mendoza noted that film sets are typically safe, but said that in this case, “I think there was some complacency on set.”

“I think there are some safety issues that need to be addressed by the industry and possibly by the state of New Mexico,” Mendoza said. “But I’ll leave that up to the industry and the state to determine what those need to be.”

Mendoza told reporters that a live round was recovered from Souza’s shoulder, which was the same round that hit Hutchins, causing her death. Mendoza identified the weapon as a FD Pietta Long Colt .45 revolver.

Mendoza also addressed rumors that the guns used on set may have been used earlier for recreational shooting, and said that investigators have not confirmed that to be true.

“We are aware of those statements and we are investigating whether or not that is true or isn’t true,” he said. “We would encourage anybody who has any information that any target practicing or any firearm was discharged away from the movie set or for practice or for whatever reason, to contact the Sheriff’s office.”

Three guns were recovered from the scene. The ammunition will be sent to the FBI crime lab in Quantico, Va., for analysis, Mendoza said.

The shooting was not captured on video, Mendoza said. He said there were about 100 people on the property at the time, but only about 16 people were in the vicinity of the shooting, which took place in a church building on the ranch.

Dave Halls, the assistant director, had handed the gun to Baldwin and said it was “cold,” meaning it that did not have any live rounds, according to a search warrant affidavit filed on Friday. Halls had retrieved the gun from a cart, where it had been placed by the armorer, Hannah Gutierrez Reed.

Mendoza said that Baldwin, Gutierrez Reed, and Halls have all cooperated with the investigation and given statements.

Souza, who was released from the hospital, told investigators that “there should never be live rounds whatsoever near or around the scene,” according to an affidavit.

Investigators retrieved spent shell casings, revolvers, clothing and swabs with blood on them from the scene on Friday, according to a search warrant return filed on Monday.

IATSE Local 480, the union that represents most film workers in New Mexico, issued a statement on Tuesday saying it was disturbed by reports that non-union workers had been hired after the camera crew walked off the set. The crew reportedly complained of poor working conditions.