6 students were injured, and the suspect has not yet been found.
Police in Aurora, Colorado, was called to a park near Central High School, where they found five injured students aged 14 to 17 years.
“In total, 5 people were taken to the hospital. The incident did not happen inside the school, but in the park,” the police said on Twitter.
Police later said six people were injured.
Colorado has seen two of the most infamous mass shootings in U.S. history.
In 1999, two teenagers shot and killed 12 classmates and a teacher at Columbine High School. Then, in 2012, a heavily armed man broke into a movie theater in Aurora, killing 12 patrons. He is currently serving a life sentence without the possibility of parole.
In March of this year, an armed man killed 10 people, including a policeman, at a grocery store near Denver.
After a year of online learning, U.S. schools have returned to classroom classes, which has revived the fear of new mass shootings, and a number of small incidents have been reported in the past few weeks.
According to data compiled by the Washington Post, more than 256,000 American students have been subjected to gun violence in U.S. schools since the Columbine tragedy. The figure includes those who were victims of violence, such as witnesses and those who were forced to leave educational institutions when the shooting began.
According to the Washington Post database, there were 29 mass shootings in U.S. schools in 2018 and 27 in 2019. These figures do not include college or university shootings, suicides, or accidental shootings.
Most people died during a mass shooting in Parkland, Florida when a schoolboy shot dead 17 students.
Every case of mass shooting provokes fierce debate and calls for reform in the field of arms sales.
Tightening gun control is supported by an overwhelming number of U.S. citizens, but Republicans have long opposed it because they believe it is an encroachment on their right to bear arms.