(NewsNation) — A teenage boy is dead and two girls are in critical condition after a shooting at an Iowa high school, according to police. They also announced suspects were in custody, but did not say how many or what charges they could face.

The boy who died was 15 years old. The two girls, 16 and 18 years old, were students at East High School where the shooting happened. The boy was not a student there, police said.

Principal Jill Versteeg described what happened as “everyone’s worst nightmare” and urged parents to “hug your students and love them.”

The shooting happened before 3 p.m. at the school in Des Moines, Iowa. The school was temporarily placed on lockdown until about 3:30 p.m., when school officials were given an all-clear to dismiss students.

Superintendent Thomas Ahart said school shootings have “become too common” and said that “real change to gun laws and access would go a long way to help us.”

“Our staff and students,” he said, “are forced to train for these incidents and the trauma associated with the repeated drills and incidents will remain with them for years to come. It’s unfortunate that our state and our country have become a place where firearms are far too easily accessible.”

Des Moines police Chief Dana Wingert went to the school after the shooting and expressed frustration at the violence.

“Unfortunately, what happened here today was just another pointless tragedy in our community,” Wingert told NewsNation affiliate WOI-TV. “People (are) using firearms to settle their differences.”

This is a developing situation. Check back for updates.