Alec McKinney

In December 2018, an anonymous parent reportedly called the Douglas County School Board of Education's director to express concerns regarding bullying and violence at the school.

A district official wrote a letter on December 19, 2018, urging the School Executive Director to investigate concerns to determine their legitimacy and to take any remedial action that may be appropriate.

The school has since filed a defamation lawsuit against the parent who had raised allegations suggesting that the school posed a risk of violence or a school shooting.

On May 7, 2019, a school shooting occurred at STEM School Highlands Ranch, a charter school located in Douglas County, Colorado, United States, in the Denver suburb of Highlands Ranch.

One student was killed and eight others were injured.

Sixteen-year-old Alec McKinney and eighteen-year-old Devon Erickson were convicted on dozens of charges and sentenced to life imprisonment.

It, along with the Columbine High School massacre, is one of the only 3 school shootings to be carried out by two individuals.

The K-12 charter school held approximately 1,850 students.

At the time of the shooting, it had no police officer assigned to it and used private security instead.

On April 29, 2019, an edit was made to the Wikipedia entry for the STEM School Highlands Ranch, stating that "anti suicide programs are implemented [in the school] to help lower chances of suicide and school shootings."

The following comment was added by an anonymous editor on the same day: "Do they work? We shall see".

KDVR described this as "a possible warning".

The IP address associated with the edit was traced to Littleton, Colorado, which is near where the shooting occurred, and no other Wikipedia edits were attributed to that particular IP address.

Eventually, the comment was removed from the page.

At 1:53 pm, Erickson and McKinney entered the school carrying handguns and other weapons hidden in guitar cases.

They opened fire in two separate locations, shooting several students.

The school proceeded to announce a lockdown, and the Douglas County Sheriff's Office issued a warning via Twitter to avoid the area, describing it as an "unstable situation".

Police responded to the school two minutes after the first 911 call and a bomb disposal robot was brought to the school after tactical gear was found inside one of the suspects' vehicles.

A direct two-way radio link from the school to Douglas County Sheriff's dispatch center is credited with the prompt response; the STEM School is one of only a few so equipped.

According to a student, Devon Erickson allegedly pulled out a gun and yelled, "nobody move".

Kendrick Ray Castillo jumped on him and was fatally shot in the chest.

Erickson was then subdued and disarmed by two other students.

This occurred in the high school section of the school, while McKinney targeted the middle school section and wounded four students before being tackled by an armed security guard.

McKinney told investigators, and later reaffirmed in an affidavit, that he had planned to commit suicide after, but his plan was thwarted when he realized he did not know how to release the safety mechanism on his handgun.

A video camera captured McKinney attempting suicide and struggling with the safety before being confronted by a security guard, whose instructions to surrender McKinney complied with.

Officers did not have to fire at the suspects prior to them being taken into custody, however, there was an instance of friendly fire during the response in which a private security guard reacted to a muzzle of a gun coming around the corner, that was later established to be held by a Douglas County Sheriffs deputy.

Authorities later confirmed that at least two handguns were used in the shooting, with three handguns and a rifle recovered.

They also went to Erickson's home and seized a car with hand-painted graffiti that read "Fuck society" as well as "666" and a pentagram.

One student was killed and eight others were injured in the shooting, two were in serious condition.

On 12 May, the last of the wounded students was released from the hospital.

Officials told reporters at the time that the youngest victim was 15 years old.

There were no staff deaths or injuries; all victims were students.

At least three students, 18-year-old seniors Kendrick Castillo, Joshua Jones, and Brendan Bialy, lunged at an attacker, later identified as Erickson.

The three students jumped from their desks and slammed the gunman against the wall.

The shooter fired off several shots as they struggled with him.

Castillo was killed in the process, the only student killed during the shooting.

Jones was shot twice, receiving non-life-threatening injuries in his leg and hip.

Bialy managed to wrestle the handgun away from the shooter during the struggle.

The two suspects, who were students at the school, were taken into custody in two separate locations following the shooting.

Local media outlets reported that the weapons used by the suspects were stolen from a parent, and that neither were known to law enforcement prior to the attack.