The Colorado charter school shooting suspects got the weapons allegedly used in the deadly attack by smashing into a locked gun cabinet at a parent’s house, according to a report.

Devon Erickson, 18, and Alec McKinney, 16, allegedly broke into the supposedly secure gun safe at Erickson’s parent’s house before Tuesday’s attack that killed a classmate and injured eight others, according to Denver7 news, citing a “high-ranking source with knowledge of the investigation.”

They also reportedly spray-painted “f–k society” and “666” on one parent’s car and torched it before the attack at STEM School Highlands Ranch, Denver7 claims.

Douglas County Sheriff Tony Spurlock has previously said at least two handguns were used, while reports say a rifle was also recovered.

Now Denver7’s sources say officials believe the guns were legally bought by Erickson’s parents and stolen by the pair, both of whom are due in court, where they are expected to be formally charged Friday.

Erickson’s mom, Stephanie Erickson, 56, previously broke down when she told The Post she doesn’t know why her son opened fire on his classmates.

“We just need a little time right now,” Erickson told The Post.

Kendrick Castillo, 18, was killed in the shooting and eight other students were injured.

Castillo was one of the students credited with charging one of the gunmen and saving others’ lives.

Erickson and McKinney — who is listed in court documents as Maya Elizabeth McKinney but who identifies as male — were both arrested on suspicion of a single count of first-degree murder and 29 counts of attempted murder in the shooting.

District attorney George Brauchler is also expected to announce whether McKinney will be tried as an adult.

With Post wires