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Arapahoe High School was locked down on Friday after the gunman opened fire. Reuters

On Friday night, authorities identified the suspect in a Colorado high-school shooting that left two students injured.

Police say Karl Halverson Pierson, 18, a male student at Arapahoe High School in Centennial, Colo., opened fire with a shotgun in the high school, reports WJLA. It is believed he was seeking revenge against a debating team coach, who is also a librarian at the school. He shot two students -- critically injuring one -- before he turned the gun on himself.

WJLA reports that students informed the coach, who exited the building in an attempt to get Pierson to follow him outside. Less than 20 minutes within receiving reports of the gunman, officers discovered the suspect's body inside the school -- dead of a suspected self-inflicted gunshot.

One of the wounded students, a female, was hospitalized and is currently in serious condition. A second student was treated for minor injuries and released from the hospital Friday evening.