Boys in blue stormed Manual High School on Thursday afternoon to reports of gunfire.
Officials say three living soul have been injured, with one person shot in the arm, another one incentive in the leg and the third person “sustained multiple gunshot wounds”.
John Caucasoid, Denver Police Department spokesman, told the Denver Channel: “All three are currently living treatment at area hospitals.”
The wounded have been rushed to medical centre.
It is unknown if the injuries are life-threatening.
Denver police department tweeted: “#DPD Constables are in the 1700 block of E. 28th Ave investigating a shooting. 3 victims transported to the medical centre. No suspect information available at this time.”
It is unclear who was in the school at the but as students had the day off.
Americans are celebrating Thanksgiving and public schools are closed for the celebration.
Information about the shooter has not yet emerged, but police said there is no pressing threat to the public.
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