Officials say the Superdome power outage during the Super Bowl was triggered by an "abnormality" in the power system.
That triggered an automatic shutdown and forced backup systems to kick in, officials said about two hours after the Baltimore Ravens beat the San Francisco 49ers 34-31.
But officials still aren't sure what caused the initial problem.
A joint statement from Entergy New Orleans, which provides power to the stadium, and Superdome operator SMG gives a chain of events.
The problem started at the spot where Entergy feeds power into the stadium's lines, and occurred shortly after Beyonce's halftime show with extravagant lighting and video effects.
"A piece of equipment that is designed to monitor electrical load sensed an abnormality in the system," the statement said. "Once the issue was detected, the sensing equipment operated as designed and opened a breaker, causing power to be partially cut to the Superdome in order to isolate the issue. ... Entergy and SMG will continue to investigate the root cause of the abnormality."
The FBI has ruled out terrorism.
The concourses didn't go totally dark thanks to auxiliary power.
— Paul Newberry — http://twitter.com/pnewberry1963