The reference I have is Storming the Eagle's Nest by Jim Ring (p 298-299). But the original reference is: The Straits of hell: The Chronicle of a Salonika Jew in the Nazi Extermination Camps, Auschwtiz, Mauthuasen, Melk, Ebensee (2005) by Moshe Ha-Elion
In Jim Ring's account
I would like in no way to suggest this was typical - obviously there were some reprisal killings, but hopefully few reprisal immolations. One possible objection is the Germans may have struggled to maintain sufficient fuel supplies to keep the crematoria running during the final collapse in early May 1945.In scenes repeated at other concentration camps across what was left of the Reich, the inmates of Ebensee then turned against those who remained of their captors. Moshe Ha-Elion recounted that one of these was a Kapo - a prisoner in charge of supervising the camp labour. Gypsy Kapo - as he was known - was notorious for his cruelty. He was captured by a group of Russian-Ukrainian Jews who were then joined by a lynch mob. They beat the Kapo to the ground and stoned him till he seemed dead. They then set off carrying him to the camp's crematorium through the cordon of cadavers. The Kapo regained consciousness and began to struggle. Someone shouted, 'Let's burn him alive!' He cried in horror, seeing the end that await him. He was dragged to the crematorium and thrown onto the iron stretcher used for offering up the bodies to the furnace, shouting and screaming at the top of his voice. 'Someone took a long bar, which served for the purpose of pushing the corpses from the carriage into the oven and thrust the hook into the Capo's groin and pushed his body into the oven....the door of the oven was shut. The cries were no more heard.'
Then again, perhaps it is well known anecdote from other sources.