The Safety Rangers are the crossing guards at Third Street School. They dress in uniform: green formal shirts and trousers, black ties, orange/yellow utility belts and black shoes. They're lead by Captain Brad.
In the episode "Officer Mikey," Mikey idolised the safety rangers and wanted to become one. He, after a series of facts and favours by the gang, was given his sash. However, he later quit after realising it was too tough for him: he had to get-up early and miss breakfast; then it would start to rain; and, during his duty, kids spat at him when he tried to stop them from skateboarding.
In the the episode "Economics of Recess," they enforced the ticket collection on the school gate and on certain areas of the playground. It is unclear whether they did this as a victor faction in the power vacuum that was created with this new currency or if they did this to enforce order and to not be a victor and, if they did so, who were they working under.