The African Union says a team sent to investigate the ongoing crisis in Burundi received reports of torture, arbitrary killings, targeted assassinations, arbitrary arrests and detentions which are of "great concern."

A delegation of the African Commission on Human and Peoples' Rights said in a statement Tuesday that an attack Friday of three military facilities by an unidentified group that left at least 87 people dead, has led to an escalation of violence and human rights violations.

Burundi has been in turmoil since President Pierre Nkurunziza sought re-election in April despite a two- term limit imposed by the constitution. The April announcement of Nkurunziza's candidacy sparked street protests that boiled over into an attempted coup in May. Nkurunziza was re-elected in July, but the violence has since increased.