Two teenagers are in critical condition after a school shooting at Evergreen High School in Colorado, while the shooter, another teenager, died from self-inflicted injuries.

The incident occurred on Wednesday, Sept. 10, around 12:24 p.m., when the Jefferson County Sheriff’s Office received reports that the student had opened fire both inside and outside the school.

Law enforcement did not fire any rounds, and after a brief lockdown, the high school, which serves about 900 students, was declared safe.

The victims, who were also students, were taken to St. Anthony Hospital in Lakewood, Colorado, with one sustaining critical injuries and the other non-life-threatening injuries.

Authorities are still investigating the shooter’s motive, and it is unclear whether the victims were known to the shooter, while state officials, including Governor Jared Polis, monitored the situation closely, USA Today has reported.

Evergreen High School is located near Columbine High School, the site of the 1999 mass shooting, one of the deadliest in U.S. history.