An email from Homeland Security officials indicates that the federal government investigated postings made on Twitter about the Super Bowl power outage before the event happened.

Cox Washington bureau reporter Scott MacFarlane obtained the emails on Friday.

One email sent at 9:54 p.m. states "Digital Sandbox, at the New Orleans EOC, has discovered 'Twitter' postings referring to 'power outages' at the venue were posted early today. All related suspicious traffic and information has been forwarded to the FBI representative at the New Orleans EOC. "

A second email sent at 10:01 p.m. updates the investigation. "All angles being reviewed. 'Digital Sandbox' is the Situational Awareness tool in use in the Operations Centers," the email states.

The power outage plunged the stadium into darkness during the third quarter of the game.

MacFarlane also obtained other emails exchanged among federal officials about the cause. "The power outage at the dome appears to be mechanical/technical issue. Power is estimated to be restored in approximately 15 mins," an email said.

It took more than 30 minutes to restore power and resume the game.

Officials said an "abnormality" in the power system triggered an automatic shutdown. A spokesman from Entergy Corp. later told the Associated Press that the blackout was caused by a faulty electrical relay installed in 2011 as part of an upgrade made in anticipation of the game.

Follow Scott MacFarlane on Twitter for updates on this developing story.