LOS ANGELES - An 18-year-old male student was killed and eight other students were injured in a shooting that occurred Tuesday afternoon at a charter school near Denver, capital of the US western state of Colorado, local police confirmed.

"It is with extreme sadness that we can confirm that 1 student at the STEM School was killed in today's #stemshooting incident. The immediate family has been notified," Douglas County Sheriff's Office tweeted about five hours after the fatal incident.

Two suspects entered the school just before 2 pm local time (2000 GMT) and "got deep inside the school and engaged students in two separate locations," according to Douglas County Sheriff Tony Spurlock.

"There were a number of students that were shot and injured," he said at a press briefing. He did not release the names of the victims and the suspects.

Both suspects were arrested by policemen, who arrived at the scene in ten minutes, Spurlock said, adding that the investigators had recovered a handgun, but had no clue on the suspects' motive.

He also announced that the school has been cleared before 5 pm local time (2300 GMT) and investigators are no longer looking for additional suspects.