An 18-year-old student at Tempe's Corona Del Sol High School shot and killed himself on the school campus this morning, police say.

Police identified the student as Marcus Wheeler.

"After the incident, the lockdown remained in place to allow investigators to keep the scene secure," Tempe police spokeswoman Molly Enright says in a statement. "There was no apparent threat to other students or staff, and this was an isolated incident."

Police say that around 8:50 a.m. today, school staff members reported to the school's dedicated police officer that there was someone on the campus with a gun.

The police officer tried to talk Wheeler into putting down the gun, but Wheeler shot himself.

Wheeler actually posted on Twitter this morning that there was "going to be a suicide in the school."

there is going to be a suicide in the school right now — TIGERHOODS?? (@marcuswheeler69) May 12, 2015

Wheeler, who previously had attended Chandler's Hamilton High School, was a cross country state champion in 2014.

The school was locked down until roughly 10:15 a.m., when students were allowed to go home, police say.

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