The people you are looking for are;
Gary Lee Rock, he graduated in 1972 from Chambersburg Area Senior High School, Chambersburg, Pennsylvania.
James William Cutchall, born April 13, 1944 in Chambersburg, Franklin Co., Pennsylvania. His parents are Chalmer H. and Frances K. Hendershot Cutchall. He graduated in 1962 from Chambersburg Area Senior High School. He has two brothers and one sister, Jeff, Carolyn and Thomas. James Cutchall died July 2, 1977 and is buried in Lincoln Cemetery, Chambersburg, Pennsylvania. He was the chief of Fayetteville Volunteer fire company.
Wilbur Brookens, was born in Fayetteville, Franklin Co., Pennsylvania on July 18, 1922 and died July 2, 1977. He is buried in Mount Pleasant Cemetery. His parents were James M. and Lulu Sheppard Brookens. He was a veteran of WWII, he served in the U. S. Army Air Corps. He was married to Catherine LaVelle Argenbright Brookens. His children are Wilma (Mrs. Samuel Hepfer) and Wilbur Jr.
I have some articles on the shooting, the articles are from the Public Opinion Newspaper, Chambersburg, Pa., dated Tuesday, July 5, 1977.
I hope this will help you out, if you would like a copy of the articles let me know and send me your address and I will send what I have.