Khilas bin Amr (may Allah have mercy on him) says that a man hired four men to dig a well. Part of it fell upon one of the men and he died. The matter was brought to Sayyiduna Ali (may Allah be pleased with him), and he placed three quarters of the blood money upon the three, and waived for them the one quarter which was the share of the dead man himself.
The narrations of Khilas from Ali (may Allah be pleased with him) are not used as evidence because they are mursal (with a break in the chain). And this is upon their 'aqilahs, if the collapse of part of it was due to their own act.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16400