The protest was planned by a group of BU Students. Black Lives Matter were in contact with the group and supported their overall cause but that was it. There were several warnings from many that this could get ugly and it did as soon as night fell.You don’t have to guess though - BLM Boston made a statement explicitly not organizing, leading or sponsoring the protest yesterday.
Guessing responsibility for violence isn’t the way to go.
BLM was scheduled to hold their rally tomorrow but I don't know if that will happen.