A wrench for securing, actuating and preventing tampering with a fire hydrant is disclosed. In useful embodiments, the wrench can be a two-ended wrench having a loop that encloses a pentagonal opening at either end of an elongated handle, where the handle can include in a nonterminal portion a slot. In a locking mode, the wrench can accept at a first end an actuating nut of the fire hydrant and can be locked in place by inserting a locking arm of a padlock through an eye bolt that is secured to a side of the fire hydrant and inserted through the slot. The wrench can be unlocked and removed, whereupon a second end can be used to turn the actuating nut as well as to remove water outlet caps and adjust nozzles.