Kharijah bin Zayd narrates from his father Zayd bin Thabit (may Allah be pleased with him) that he said, regarding people who would inherit from one another but who died by drowning or perished from some other cause, and it was not known which of them died first: They will not inherit from one another.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12252