For the third time in a month, security officials have confiscated a large cache of weapons hidden in an educational institution in northern Israel. The haul on Monday in the Arab village of Abu Snan in the western Galilee included handguns, rifles, and even mortar shells. Police believe that the weapons were being stored by criminal groups.

Police moved in on the school after getting a tip that weapons were being stored at the school. Bomb squad experts and top security officials in the Northern district descended on the school and dismantled 13 mortar shells, and confiscated dozens of weapons and hundreds of nine millimeter bullets. Police have opened an investigation into the incident and are questioning school officials.

In a statement, police said that the seizure was “part of the department’s ongoing and unyielding efforts to fight crime.”

Last month, a kindergarten teacher summoned police after she found a large cache of weapons in a children’s playground. The weapons had been buried in sand, with some of the weapons jutting up out of the sand. A week later, another cache was found in Abu Snan, in a park next to a kindergarten. Police found RPG rockets, explosives, and Lau missiles in that cache. All the weapons were destroyed.