Gardeners in the Israeli city of Nazareth Illit discovered a bag containing about 25 ISIS flags.

Israel Police have opened an investigation into the discovery of the flags on Tuesday in an industrial area of northern Israeli city. The possession of materials from the jihadist group was outlawed in Israel several weeks ago.

“When something like this is discovered in the heart of a Jewish city, it needs to light up many warning signs,” Nazareth Illit Mayor Alex Gadalkin told Ynet.

In late September, a 24-year-old Arab-Israeli from Kfar Kana who was suspected of being associated with ISIS was arrested and questioned.

Earlier in the month, another Arab-Israeli was arrested for allegedly traveling to Syria and training with ISIS. Contact with the group also was made illegal.