Local authorities were warned two and a half months prior to the massacre in a Florida high school that accused shooter Nikolas Cruz had “used a gun against people before,” according to a disturbing new report.

The chilling details on Cruz’s troubled past were revealed in 911 records obtained by CNN.

Cruz, 19, began acting violent shortly after he and his younger brother, Zachary, moved into neighbor Rocxanne Deschamps’ trailer home following their mother’s death in November.

Palm Beach County sheriff’s deputies were called to the trailer three times in less than a week — for a report of a weapon and a fight between Cruz and Deschamps’ 22-year-old son, Rock.

The day before Thanksgiving, Rock called 911 to report that he believed Cruz, whom he described as an “adopted 19-year-old son,” had hidden a “gun in the back yard,” according to the 911 dispatcher’s notes.

Rock told authorities “there were no weapons allowed in the household,” the report said.

It’s unclear whether a search of the property in Lantana was conducted and the call was classified as “domestic unfounded.”

Four days later, Cruz erupted into rage after losing a photo of his dead mom and began punching walls.

He then started fighting with Rock — and left the home.

Rocxanne called 911, telling the dispatcher that Cruz said “he was going to get his gun and come back” and that he’d “bought a gun from Dick’s last week and is now going to pick it up.”

She also said Cruz had “bought tons of ammo” and “has used a gun against ppl before,” the notes said. “He has put the gun to others’ heads in the past,” Rocxanne added.

When deputies responded, Cruz and Rock “hugged and reconcile[d] their differences.” Cruz also “said he was sorry for losing his temper.”

Rocxanne declined to press charges, telling authorities she didn’t want Cruz going to jail because he’d been “going through a lot” after his mom’s death, according to WPTV.

The day before the fight between Rock and Cruz, a social worker from Marjory Stoneman Douglas High School asked deputies to check on Zachary Cruz, WPTV reported.

The 17-year-old boy hadn’t shown up at school since his mother died, but he “was never disenrolled from school in Broward to attend any other school,” the social worker said.

Deputies visited the trailer but were told to come back later. It’s unclear if they did.

Rocxanne’s ex-fiance Paul Gold, a longtime neighbor of the Cruzes in Parkland, recalled how Nikolas Cruz was upset that no one showed up for his mom’s funeral, CNN reported.

“The boy was stoic. Not a tear. Not an emotion,” said Gold, who drove Cruz to the funeral. “I asked him if he was upset. He said: ‘I’m upset because nobody came, and nobody cares about my mother.’”

“I told him that his mother was loved by many, many people and they just couldn’t make it, timing and whatnot,” Cruz added. “It was a complete lie. But I felt horrible. Here’s this poor kid, and his mother dies, and not a soul shows up.”

The only people who went were Cruz, his brother, Gold and Rocxanne.

Gold said he wasn’t aware that Cruz had guns and called him a “monster.”