Police arrested a juvenile Wednesday afternoon in connection with graffiti threats made at an Oahu middle school on Friday, a Honolulu police spokeswoman said in an email.

The juvenile, whose age and gender were not released, was arrested on suspicion of first-degree terroristic threatening, police said. The case will be referred to Family Court.

The Honolulu Police Department did not identify the school, but students were locked in their classrooms for about an hour Friday morning at five schools in the Ewa-Kapolei area. The schools are Campbell High School, Ilima Intermediate and Kaimiloa, Pohakea and Ewa Beach elementary schools.

Students were kept in classrooms from 10:15 to 11:35 a.m., just before lunch, the Department of Education reported.

Several students posted photos to social media accounts of a threat apparently written on a wall that included a crude drawing of a gun firing at stick figures. The graffiti message alluded to “m9 beretta” and warned to “Watch out, 11:05 a.m.”

Also, the state Department of Education increased the presence of security personnel at Castle High School in Kaneohe and nearby areas Friday morning, after school officials were made aware of a reported threat made the previous day.