Assistant director Dave Halls reportedly told Baldwin the prop firearm didn't contain live rounds minutes before the incident.
Sunny Hostin called the behavior "disgusting and despicable."
"She had a spunk and passion that infected the entire crew from the top down."
According to a warrant, the gun handed to Alec Baldwin just before the fatal shooting was loaded with a live round.
The accident took place on Oct. 21, while filming Joel Souza's upcoming western movie.
"There are no words to convey my shock and sadness regarding the tragic accident," Baldwin wrote in a tweet.
According to an email from IATSE Local 44, the gun used on set contained a live round.
Actor Brandon Lee died in a fatal prop gun misfire incident in 1993 while filming The Crow.
The cinematographer died in the midst of filming the upcoming western film Rust.
"Detectives are investigating how and what type of projectile was discharged."