(JTA) — A giant swastika was formed out of large white tiles on a San Francisco high school football field.

Custodians at El Camino High in South San Francisco discovered the image Monday on the 40-year-old line, the San Francisco Chronicle reported Tuesday. The swastika, which was believed to have been placed on the field after the school’s graduation ceremony on Friday afternoon, was removed the day it was found.

Local residents reportedly noticed the swastika over the weekend, with some taking photos to document it.

The swastika was dismantled without causing any permanent damage to the field, which was put in last year, according to the newspaper.

“When I saw a giant swastika on the field, I was really pissed off,” Robin Braun Belinsky told the Chronicle. “It was an ugly thing to see — really jarring.”

Belinsky recalled being teased as a child for being Jewish and called for the vandals to be punished.

South San Francisco police have launched an investigation into the incident.