One suspect was in custody Wednesday afternoon after a shooting at a Northwest D.C. public high school, police said.

What caused the shooting was not entirely clear Wednesday evening. But police and schools officials said that after a verbal altercation between two juvenile male students at Coolidge Senior High School during the day, one returned at about 3:15 p.m. as students were being dismissed and shot the other.

Soon after, police said, the injured student was being treated at a hospital for injuries not thought to be life-threatening. The suspected shooter was in custody but had not been charged as of just before 5 p.m. Neither was identified by authorities.

At press conference outside the school, D.C. Schools Chancellor Kaya Henderson called the shooting an “isolated incident,” and said “parents should feel safe bringing their students to school” Thursday.

Extra staff, including counselors, will be available at the school Thursday, Henderson said.

The student who was injured was shot in the leg, according to Assistant Police Chief Roger Newsham, who said a gun was recoverd at the scene.

The shooting took place in the area of the school’s football field a few hundred feet from the school’s front entrance on Sheridan St. The school was put on lockdown shortly after the shooting as police cleared the crime scene; students and others inside were later allowed to go home.

This item has been updated.