So BP conducted an internal study of the oil spill gush and found that several companies were culpable as well. (Executive summary pdf)
The team did not identify any single action or inaction that caused this accident. Rather, a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident. Multiple companies, work teams and circumstances were involved over time.
Ah, so BP has taken the American route by blaming other people as much as possible for their mistakes.