Heavily armed police rushed into Arapahoe High School following reports of an "active shooter"
Two students have been injured in a Colorado school shooting, the Arapahoe County sheriff has said.
A student believed to be the gunman who had entered the school with a shotgun has been found dead of a probable self-inflicted gunshot wound, police said.
The sheriff said the gunman was looking for a specific teacher, who left the building. A student confronted the gunman and was shot.
It is unclear how the other student received a minor injury.
The school and others in the area were placed on lockdown but Arapahoe County Sheriff Grayson Robinson indicated the threat had ended.
When police entered the school, they discovered another student who had a minor wound.
Authorities later found what they believe to be the shooter, dead from an apparent self-inflicted gunshot wound, Sheriff Robinson said.
Students could be seen on television footage streaming out of the school in single-file lines with their hands above their heads during the police search on Friday.
The school is said to have more than 2,200 students and 70 classrooms.
The building is just eight miles (13km) east of Columbine High School in Littleton, Colorado, the site of a mass school shooting in April 1999 which left 14 students dead.
The shooting was reported the day before the anniversary of the shooting in Newtown, Connecticut, in which 20 schoolchildren and six workers were killed at a primary school.