Three teenagers remained in critical condition Wednesday after a shooting at Evergreen High School in the Denver suburbs, authorities said, with the suspected shooter among those hospitalized.

The incident occurred at about 12:30 p.m. local time at the school in Evergreen, Colorado, Jefferson County Sheriff’s Office spokesperson Jacki Kelley told the Associated Press. All victims taken to the hospital are believed to be students, and the suspected shooter is thought to be a student at the high school.

By midafternoon, the three teenagers were either in surgery or being treated in the emergency room at St. Anthony Hospital in Lakewood, Kevin Cullinan, the hospital’s chief executive officer, told the AP. Cullinan said he did not believe there were additional victims. Details about the victims’ injuries were not immediately available.

Investigators had not released the identity of the suspect or confirmed whether more than one shooter was involved. Jefferson County authorities said none of the law enforcement officers who responded to the scene were believed to have fired their weapons. It was not immediately clear whether the shooting occurred inside the school building or on school grounds.

Law enforcement at the scene near Evergreen High School

FBI Director Kash Patel posted on X that the agency was on scene and providing support to local authorities. Colorado Gov. Jared Polis said he was closely monitoring the situation and that state troopers were supporting local law enforcement. "Students should be able to attend school safely and without fear across our state and nation," Polis wrote on X.

More than 100 police officers from the Denver area responded to the incident at the high school, which has an enrollment of more than 900 students. The Jefferson County Sheriff’s Office was the primary responding agency; it also was the lead agency that responded to the 1999 Columbine High School shooting, which killed 14 people.

Police and emergency personnel outside Evergreen High School

The Jefferson County Sheriff’s Office did not immediately respond to a request for additional comment from Fox News Digital. Authorities said the investigation was ongoing and urged members of the public to avoid the area while first responders and investigators remained on scene.

School officials and local leaders did not release further information about the circumstances leading up to the shooting or the condition of the students beyond what hospital and law enforcement officials had provided. The FBI and local authorities did not immediately offer a timeline for when more details would be available.

As investigators worked to establish the facts, officials reiterated that the matter remained under active investigation and asked anyone with information to contact law enforcement. The response drew state and federal resources to the site as officials sought to ensure the safety of students and staff and to determine what happened during the midday incident.