SAN DIEGO -- A 15-year-old boy who was shot and killed by police after he pointed a BB gun at them in a high school parking lot in the middle of the night had left a suicide note, officials said Monday.

Assistant Police Chief Brian Ahearn told the Associated Press that police found the note on the Torrey Pines High School student after the fatal incident over the weekend.

"We believe that he called the police and pulled the gun on them so that he would be shot," Ahearn said.

Police say the boy called 911 shortly before 3:30 a.m. Saturday to ask officers to check on the welfare of boy in front of the school.

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When two officers arrived, they spotted a youth in the front parking lot. As they got out of their patrol cars, he pulled a gun from his waistband and pointed it at an officer, police said.

The officers drew their guns and ordered him to drop the weapon. But instead he began to walk toward an officer, ignoring more demands to drop the weapon, police said.

Both officers fired, hitting him several times. They performed first aid and called paramedics. The teen was pronounced dead at a hospital.

The gun was found to be a BB air pistol. Investigators determined the teen made the 911 call himself.

Police didn't release the teen's name because of his age.

The San Diego Union High School District said in a statement that it was sending a crisis-response team to the campus Monday to support students, staff and parents. Counseling was also made available at all schools in the district for anyone wanting to talk about the shooting. Principal Rob Coppo told CBS affiliate KFMB he would also withhold the name the teen along with personal details about him in line with his family's wishes.

"Our family is mourning the loss of a loving and wonderful young man," the victim's mother said in a statement released to KFMB. "We ask that you respect our privacy as we remember him and all he meant to us."

A makeshift memorial of notes and flowers was placed outside the school after the shooting.

"It's impossible to think that someone that young, with their whole life in front of them, would force something like this," a parent told KFMB.

The two officers involved in the shooting have been placed on administrative duty until the investigation wraps up, the station reports.