CAPE GIRARDEAU, Mo. (AP) — Two people were injured when gunfire broke out during a high school graduation commencement in Missouri, causing hundreds of people to scatter and forcing the ceremony to be postponed.

The shooting happened around 2:30 p.m. Sunday in Cape Girardeau, a city of 40,000 residents about 115 miles (185 km) south of St. Louis. The two people injured were not students. Both are expected to survive, police said in a statement.

Police said an altercation between two people led to the shooting inside the Show Me Center. School resource officers detained one person and assisted the two victims, who were hospitalized with what police described as non life-threatening injuries.

“During our graduation ceremony today at the Show Me Center, an altercation occurred forcing us to stop the ceremony and evacuate the building,” Cape Girardeau Public Schools Superintendent Howard Benyon said in a statement. He said the ceremony will be rescheduled.

Police said a person of interest was in custody. Charges had not been filed as of Monday morning.