St. Louis school shooter had his rifle taken away from him days before attack, officials say

About a week before a 19-year-old shooter opened fire Monday inside a St. Louis high school, his family told police he had a gun and had it removed from the home, officials said Wednesday.

The family were aware the gunman had mental health struggles and did “everything that they possibly could have done” to help him —including getting him therapy and medication and committing him on several occasions — but “sometimes that’s not enough,” interim St. Louis Police Chief Michael Sack said at a news conference.

Police said that earlier this month, the gunman's mother found an AR-15-style rifle in the family's home and wanted it removed.

"While it is not yet clear when or how the suspect came to be in possession of the firearm after this incident, we can confirm that the firearm involved in this incident is the firearm used" at Central Visual and Performing Arts High School on Monday, police said in a statement Wednesday evening.

The chief declined to discuss how the gunman entered the building despite locked doors, security guards and metal detectors.

"I understand that that’s something everybody would like to know, but the reality is every building — a school, a business, a police headquarters — has weaknesses," Sack said, adding that sharing the specifics of how the shooter entered the school could adversely affect the school district.

Asked whether the gunman had to break glass to enter the building, Sack said he "did have to force entry."

Shooter's mother wanted gun 'out of the house'

The shooter's family were “aware” that he had obtained the gun, although it's not clear when he got it, Sack said. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives is investigating to track the source of the gun sale.

In a statement Wednesday evening St. Louis police said that the department received a call on Oct. 15 at 5 p.m. for a “domestic disturbance” at the suspect’s residence.

Officers found that the suspect’s mother located a firearm — the same one used in the Monday school shooting — at the home and wanted it removed, police said.

The family “worked with our department to transfer that to an adult who could legally possess one,” Sack said.

The firearm was ultimately transferred to a third party known to the family.

"The mother wanted it out of the house, so they facilitated it. The party had it. How he acquired it after that, we don’t know. We’re looking into it," he said.

Initially Sack said he believed the police interaction took place within the past few months, and the department later clarified it took place merely nine days before the school shooting.

Family 'made every effort' to aid shooter's mental health

The shooter's family has been cooperating with police, Sack said.

“The mother, the adult daughter, they worked with him. They kind of had a system where they would track what might come in the mail, his interaction with others and try to make sure that he’s engaging people, that he feels loved,” he said.

The shooter, who left behind a note describing himself as a loner and referring to mass shootings, died after an exchange of gunfire with law enforcement.

Jean Kuczka, 61, a health teacher, and Alexzandria Bell, 15, a student, were killed, officials said.

“Mental health is a difficult thing. It’s hard to tell when someone is violent and going to act out,” Sack said.

“I’ve got to give credit to the family — they made every effort that they felt they reasonably could," he added. "That’s why the mother is so heartbroken over the families that paid for his episode."

This article was originally published on NBCNews.com