Court documents showed that Blaec Lammers had purchased assault rifles and more than 400 rounds of ammunition.
His mother had told authorities on Thursday that her son had purchased weapons similar to those used by James Holmes, the Colorado movie theater massacre shooter, CBS news reports.
"Blaec Lammers stated that he had a lot in common with the people involved in (recent mass shootings),"
court documents said. "He stated that he was quiet, kind of a loner, had recently purchased firearms and didn''t tell anybody about it, and had homicidal thoughts."
According to a report by KCTV, Lammers admitted to the police that he had bought a rifle on Monday and another on Tuesday with the intention of shooting audience members who attended a showing of The Twilight Saga: Breaking Dawn: Part 2 at a theater in Bolivar.
He also planned to continue shooting at a local Walmart because he thought he could have access to additional ammunition, the report said.