The injured along with another were in the process of changing a tire on a 6 person diesel personnel carrier. They were in the process of loosening the lug nuts on the wheel when the 4 way lug wrench came off the nut allowing 1 arm of the wrench to strike the injurer's gloved 5th finger of EE's right hand between the wrench and fender resulting in a laceration requiring 3 sutures.