Administrators at School Without Walls High School in D.C. are investigating an incident involving “inappropriate language” and a swastika drawn on the wall of a boy’s restroom earlier this week.

In a letter to parents Thursday, associate principal Sylvia Isaac said the administration “will not tolerate acts of bigotry and hate in the school community.”

“We take this very seriously, and we will address incidents and behaviors that do not conform to our community values and norms,” Isaac said.

The vandalism came a month after a someone posted “racist images” on a student’s Instagram account.

The incidents at the selective public high school in Northwest came as other schools around the country in recent months have dealt with racial and anti-Semitic incidents. This week two Jewish schools in the Washington region received bomb threats, disrupting classes and leading police to sweep campuses in Maryland and Virginia.

Isaac said the school administrators immediately asked security to review the school’s cameras to determine who went into the bathroom, but the tape showed too many students “to be able to effectively investigate each one of the boys.”

D.C. Schools Chancellor Antwan Wilson said in a statement: “These signs of hate are not acceptable and in no way reflect the staff and students at D.C. Public Schools.”