TAMPA, Fla. (WFLA) — Hillsborough County deputies rounded up 40 sex offenders during a “Halloween Operation” checking for compliance with their probation.

In a Monday release, the Hillsborough County Sheriff’s Office said deputies contacted 123 offenders in order to make sure they were following the rules.

In total, 40 offenders were arrested, with deputies saying that 37 of them had violated their probation.

However, 21 of the sex offenders were arrested on new felony charges. Deputies seized several electronic devices in the operation, and more charges are expected once the devices are analyzed.

“I am grateful to all of our law enforcement partners, and the hardworking and dedicated employees of teamHCSO for their work in ensuring that our community is safe this Halloween,” Sheriff Chad Chronister said. “There is nothing scarier than the thought of our children in the dangerous grasp of a predator.”

Halloween operations are done yearly by local and state agencies, according to the sheriff’s office.