By Angélica CasasBBC News, in Nashville

Averianna Patton is thought to be one of the last people the Nashville school shooter messaged before the attack.

On Monday morning, Ms Patton received a message on Instagram from her former classmate, who sounded depressed and desperate.

"She said that I would see her on the news later on… and something tragic was about to happen," Ms Patton told BBC News.

She immediately called the local sheriff's office.

"I don't know what she was battling... but I knew it was a mental thing, you know?" Ms Patton said.

"Just something in my spirit, when she reached out, I just jumped into the mode of trying to call around make sure that I'm doing everything that I could."

But within minutes, Audrey Hale attacked the Covenant School, killing three nine-year-old pupils and three staff members.

"I later found out that this was not a game, this was not a joke, it was [Hale] who did this," she said. "It's just been very, very heavy."

Ms Patton said that police came to her home that afternoon to review the messages from Hale.

"I'm still trying to wrap my head around what we're going through as a city and trying to find solutions to prevent this from happening again," she said.

Ms Patton, who is a local TV personality and influencer in Nashville, said she and the shooter were once teammates on the same middle school basketball team.

The suspect, Ms Patton said , could be "standoffish" at times.

But the shooter remained in contact with teammates over the years, and occasionally attended Ms Patton's events in the city.

Ms Patton said she last saw the shooter earlier this month.

Now, she's left turning over the same question plaguing Nashville residents and indeed the rest of the country: why?

"I am asking that the same thing. And I guess you know, just we'll never know. And I'm really sorry.

"I would have never in a million years imagined this."

ncG1vNJzZmivp6x7o67CZ5qopV%2Bjsri%2FjrCmq6SUYsK0ecKapZqckWKDdn2Pb25vaw%3D%3D