Story highlights "Horrific terrorist operations were thwarted," the Saudi Press Agency reported

Suspects are accused of carrying out a May attack on a Qudayh mosque that killed 21

(CNN) Saudi Arabia has arrested 431 people who are part of a "network of cluster cells linked to the terrorist ISIS organization," according to the state-run Saudi Press Agency.

"Horrific terrorist operations were thwarted," SPA said, including a suicide attack on a mosque that can accommodate 3,000 worshipers, housing for security forces and an unnamed diplomatic mission.

Thirty-seven security forces and citizens were killed during the operations, along with six terrorists, SPA said.

The suspects planned operations, surveyed attack sites, prepared suicide bombers and manufactured explosive belts, SPA said. The press agency described the actions of one group, saying they transported a suicide bomber wearing an explosive belt to a mosque in Qatif and returned later to photograph the scene.

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