Six Flags Great America and its Hurricane Harbor water park are bringing back their chaperone policy a week after shots were fired in the Great America parking lot.

Six Flags Great America re-implements a chaperone policy due to safety concerns, requiring minors under 16 to be accompanied by an adult. The policy is strict from July 17-20 and evenings after that.

According to the policy, all guests 15 and younger must be with a parent, guardian or adult chaperone 21 or older to enter the park starting at 4 p.m. Six Flags noted, though, that it may start the requirement earlier than for 4 p.m. on occasion.