A student opened fire with a handgun at Evergreen High School in the foothills west of Denver on Wednesday, injuring two other teenagers before shooting and wounding himself, authorities said.

The shooting was reported about 12:30 p.m. at the school in Evergreen, Colorado, roughly 30 miles west of Denver. Shots were fired both inside and outside the building, and responding officers located the shooter within five minutes of arriving, Jefferson County Sheriff’s Office spokesperson Jacki Kelley said. None of the law enforcement officers who responded fired their weapons, Kelley said.

More than 100 police officers from surrounding jurisdictions rushed to the scene, Jefferson County officials said. The three teenagers were taken to St. Anthony Hospital and were initially listed in critical condition, hospital CEO Kevin Cullinan said. By early evening, one of the teens had been upgraded to stable condition with non-life-threatening injuries, Dr. Brian Blackwood, the hospital’s trauma director, said. Officials did not release the ages of the victims.

The high school, which has more than 900 students and is largely surrounded by forest, sits about a mile from the center of the town of Evergreen, which has a population of about 9,300. After the shooting, parents gathered at a nearby elementary school to await reunification with students, and officials worked to reunite families with children who had sheltered in the area.

Wendy Nueman, whose 15-year-old daughter is a sophomore at Evergreen High, said her daughter initially could not be reached by phone and later called from a borrowed device. "She just said she was OK. She couldn’t hardly speak," Nueman told The Denver Post. She said her daughter ran from the school after hearing the shots.

Eighteen students who fled during the shooting sought shelter at a nearby home after pounding on the door, resident Don Cygan told Denver television station KUSA. Cygan, a retired educator, said his wife, a retired nurse, comforted and treated the students for shock while he recorded the names of students and the parents who arrived to pick them up. One student told Cygan he had heard gunfire in the school cafeteria and ran out.

The shooting revived painful memories of the 1999 Columbine High School massacre in Jefferson County, which killed 14 people. Authorities noted that one of the Columbine victims who had long struggled with injuries related to that attack died earlier this year of complications from those injuries.

Sheriff’s office and school officials said an investigation into the shooting was underway, and they did not immediately release further details about the shooter’s identity, motive or the exact circumstances that led to the attack. The school and local law enforcement urged anyone with information to come forward.

Students and parents received support from local officials and community members in the hours after the shooting, and school officials coordinated to address students' immediate safety and reunification needs. County and school leaders did not provide a timeline for when classes would resume or other long-term plans for the school following the incident.