A days-long lockout at Denver’s South High School ended Friday afternoon after Denver police found and arrested a juvenile student who had allegedly made a threat against the school, a district spokesperson said.

“The school is returning to normal operations,” Denver Public Schools spokesperson Anna Alejo said.

South High Principal Bobby Thomas in an earlier message to the school community described the student as a runaway. He said law enforcement agencies across the state were actively looking for the student and could arrest him on an outstanding warrant.

The South High lockout began Wednesday, just one day after a fatal shooting at a suburban Denver high school. A lockout is less serious than a lockdown. In a lockout, schools lock their exterior doors, and students and staff members remain inside. Classes continue as usual.

South High is Denver’s second-biggest school, serving nearly 1,600 students in grades nine through 12. In one of his first messages to parents on Wednesday, Thomas said the police “shared with us that they do not believe there is a credible threat to our school.” He explained that South continued its lockout “out of an abundance of caution.”

The school was in lockout all day Thursday and part of the day Friday, as well.

“While Denver Police continue to investigate this matter and attempt to locate the student, we will continue to take all steps necessary to ensure that the South community is safe and protected,” Thomas wrote in another message to parents Thursday night.

South High canceled Advanced Placement exams scheduled for Friday and had mental health counselors available to speak with any students experiencing anxiety, Thomas wrote.