CENTENNIAL, Colorado - The student who opened fire inside a Colo. high school Friday wanted to confront a specific teacher, but ended up fatally shooting himself after being confronted by another student, said Arapahoe County Sheriff Grayson Robinson.

Robinson said that two other students were also injured in the incident at Arapahoe High School in Centennial, Colo.. The Associated Press is reporting that a spokesman for the Littleton Adventist Hospital said one student was in critical condition and was in surgery.

The sheriff said another student has "a very minor wound" that may not have been from gunfire.

The school was placed on lockdown and students exited the building with their hands up in a single file line. As each filed past law enforcement they were patted down and then allowed to put their arms down.

The only weapon found was the one believed to have been used in the shooting, said the sheriff.

The Denver Post reported that a spokesperson for the local fire department received a call reporting a fire at the school at 12:30 p.m.

According to CBS Denver, Arapahoe High School has more than 2,000 students. It is located about eight miles from Columbine High School, scene of a mass school shooting in 1999.

Tomorrow marks one year since the school shooting in Newtown, Conn. that claimed the lives of 20 first-graders and six adults at Sandy Hook Elementary School.