St. Paul’s Central High School was on lockdown for 85 minutes on Monday morning as officers investigated a fight and searched for a possible gun. An Airsoft gun, which resembled a real gun, and three knives were found, according to police.

Officers responded to the school at 275 N. Lexington Parkway about 10:15 a.m. on a report of a fight in a restroom, said Steve Linders, a St. Paul police spokesman.

“At one point, one of the participants in the fight allegedly flashed a gun in his waistband,” Linders said Monday morning. “This caused quite a commotion.” People scattered and left the bathroom.

A couple of minutes later, there was a confrontation between the 14-year-old student who allegedly displayed the replica gun and a 15-year-old student, Linders said. The 15-year-old student punched the 14-year-old and knocked him to the ground, according to police.

Central High School Principal Mary Mackbee told parents in a letter Monday that two students made plans over the weekend to fight each other at school. A verbal confrontation turned physical in the hallway during an early lunch period, and other students followed to watch, Mackbee wrote.

The school received reports at the same time about a weapon being shown in a bathroom before the fight, and authorities found an unloaded BB gun and three foldable knives, which were not used during the altercation, according to Mackbee. Police said the Airsoft was in a backpack.

The 14-year-old was taken to a hospital and apparently was found to have no injuries, Linders said.

Police arrested the 15-year-old who allegedly punched the 14-year-old on suspicion of aggravated assault and he was booked at the Ramsey County juvenile detention center.

The 14-year-old’s 15-year-old stepbrother was in the bathroom with him when the Airsoft was displayed and may have had a knife or knives on him, according to Linders. He said both teens would be arrested on suspicion of terroristic threats and possession of a BB gun in school.

The school discovered “that some students knew about the potential for a fight before it happened,” Mackbee wrote to parents. “Please emphasize that it is important for your child to report any concerns they have about school to a trusted adult. I will not tolerate any behavior that puts our school, students or staff at risk. There are severe consequences for students who behave this way.”