DENVER (AP) — A shooting at Evergreen High School, located about 30 miles west of Denver, has left three teenagers hospitalized in critical condition. The incident occurred around midday, with authorities confirming that all of those injured are believed to be students. Specific details on the nature of their injuries have not yet been disclosed.

St. Anthony Hospital in Lakewood, Colorado, reported that as of mid-afternoon, the injured students were either in the emergency room or undergoing surgery, according to CEO Kevin Cullinan. Importantly, he noted that there were no other victims from the shooting.

The identity of the shooter or whether multiple shooters were involved remains unclear, and the investigation is ongoing. Over 100 police officers from around the Denver area rapidly responded to the scene to provide assistance and ensure the safety of the students and staff.

The Jefferson County Sheriff’s Office has a historical connection to school shootings, having previously responded to the tragic Columbine High School shooting in 1999, a dark event that resulted in the death of 14 people.