On April 29, 1945 members of the 1st Company, 3rd Battalion, 157th Infantry, under the command of Lt. Col. Felix L. Sparks, entered Dachau. There they discovered a train of 36 boxcars bearing the corpses of prisoners who had been transferred to Dachau from other camps in the last weeks of the war. As the soldiers advanced, they found stacks of bodies in other parts of the camp and thousands of emaciated survivors. They rounded up the remaining camp guards as they found them. At some point, it was reported, one of the Gis blurted out, "No prisoners!" Approximately 60 guards were then lined up against a wall and gunned down by members of the 1st Company. Others were shot in one of the boxcars or beaten to death outside with the participation of a few survivors. Pfc. John Lee and others from the unit were later summoned by military investigators to give testimony about the killings and to supply photographs. A report was written and submitted to General George Patton, commander of the 3rd Army, who chose not to take any action. The report, a copy of which was deposited in the National Archives, remained secret until 1991, when it was quietly declassified.
[Source: Wood, David, "For Memorial Day, A Painful Inquiry into the Grim Nature of War," May 22, 2001 (e-mail submission from firstname.lastname@example.org)]
See Also "Dachau Main Camp" in Encyclopedia of Camps and Ghettos, Volume 1, Part A.
See Also https://www.ushmm.org/wlc/en/article.php?ModuleId=10005131.