فَأَقْبَلَ بَعْضُهُمْ عَلَىٰ بَعْضٍ يَتَلَاوَمُونَ (Then, (at the beginning,) they started reproaching one another; 68:30). That is to say, at the beginning they made admission of guilt, but then they turned to face each other in mutual accusation, blaming each other for the punishment that visited them, whereas the crime was not committed by only a single person from among them, but it was committed jointly by all or most of them.
A note of caution
A common misdeed, in our days, is that when a calamity befalls a group of people due to their collective conduct, an additional scourge that befalls them is that, (instead of reforming themselves,) they start wasting their time in accusing each other.