Hadith: Whoever is killed in ambiguous circumstances, or when people are throwing stones, or by a whip, his blood money is the blood money of unpremeditated killing. Whoever is killed intentionally, retaliation becomes due. If anyone tries to prevent it, upon him is the curse of Allah, the angels, and all people

عن ابن عباس، قال: قال رسول الله صلى الله عليه وسلم : «من قُتِلَ في عِمِّيّا، أو رِمِّيَاً يكون بينهم بحَجَرٍ، أو بِسَوْطٍ، فَعَقْلُهُ عَقْلُ خطإ، ومن قَتَلَ عَمْدَاً فَقَوَدُ يَدَيْهِ، فمن حَالَ بينه وبينه فعليه لعنة الله، والملائكة والناس أجمعين».
[صحيح] - [رواه أبو داود والنسائي وابن ماجه]

‘Abdullāh ibn Abbās (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: ''Whoever is killed in ambiguous circumstances, or when people are throwing stones, or by a whip, his blood money is the blood money of unpremeditated killing. Whoever is killed intentionally, retaliation becomes due. If anyone tries to prevent it, upon him is the curse of Allah, the angels, and all people.”
Sahih/Authentic. - [Ibn Maajah]

Explanation

This Hadīth shows that anyone who is killed among people who were throwing objects at each other, or killed in ambiguous circumstances due to crowd or the like, and the killer is unknown, then the blood money will be like that of accidental murder, to be reimbursed by the Muslim treasury. However, in case of intentional killing, legal retribution is due. Anyone who prevents the guardians of the killed person from taking retribution, after having demanded it, has exposed himself to divine curse. Allah will not accept his repentance, religious duties, or voluntary good deeds, due to the gravity of his crime.