ST. LOUIS – The family of a gunman in Monday’s deadly school shooting in St. Louis previously reported to police that he had acquired a gun and worked with officers to transfer it elsewhere months before the tragedy.

A 19-year-old gunman, Orlando Harris, killed two people Monday morning in a shooting at Central Visual and Performing Arts High School. Police later shot and killed the gunman, who hurt several others in the incident.

Police say it’s unclear how Harris ended up with the firearm used in Monday’s shooting, and whether it was the same one that the family had previously reported to police.

St. Louis interim police chief Michael Sack noted in a Wednesday news conference that Harris was under treatment for mental issues and the family had committed him in the past. He says the family had a system for checking in on Harris, frequently checking his mail and room and monitoring his interactions with others.

“They worked with our department to transfer that to an adult who could legally possess,” said Sack. “The mother [and] the adult daughter worked with him.”

Police say the gunman’s family is “heartbroken” over what unfolded in Monday’s shooting at a south St. Louis school and is being “fully cooperative” with the investigation.

Top Story: Family previously reported gun to police before St. Louis school shooting

Sack noted that Harris’ mother was aware of his mental health struggles and tried to help him work through it.

““[The mother] is heartbroken for the families of the victims and the school,” said Sack. “They always tried to work to get him back on medication, therapy or whatever needed.”

Orlando Harris entered the building with only one weapon, an AR-15 rifle, but with more than 600 rounds of ammunition. (Photo courtesy: St. Louis Metropolitan Police Department)

Investigators say Harris entered the south city school Monday morning with an AR-15 rifle and more than 600 rounds of ammunition. While the exact motive has not yet been determined, police presented some documents Tuesday, including a handwritten note in a car tied to the gunman, that hinted toward mental health struggles.

Police confirmed Wednesday that Harris was the only gunman tied to the incident and that CVPA High School appeared to be the target, not an individual.

Mayor Tishaura Jones and Missouri Congresswoman Cori Bush also renewed their calls for more gun control legislation in Wednesday’s press conference.

“St. Louis has had enough. We are beyond enough,” said Bush.

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Jay Greenberg with the FBI Division of St. Louis adds, following Monday’s shooting, there have been an increase in “hoax threats” made toward St. Louis area schools in recent days. As a result, the law enforcement presence has increased at several schools this week.

“We ask for everybody’s help here to make sure we have these get these hoax threats ramped down so that law enforcement can do the job they need to, and we can continue to get services out to all the victims of the broader community,” said Greenberg.

CVPA High School will be closed for the next several weeks as district officials work to determine the next steps.