An arc flash is to blame for a recent incident of power problems and multiple outages at Bradley International Airport in Windsor Locks, CT but officials are still investigating exactly why the backup systems didn’t kick in when the situation occurred.

Airport authorities said the arc flash knocked out power to their cogeneration plant, the airport’s primary source of power, as well as Eversource utility power equipment that powers the backup system.

The power problems impacted the airport's TSA screening area and no screening was taking place for hours. A crowd of people could be seen standing in the dark near the TSA checkpoint around 4 a.m.

Hundreds of people were stranded in the terminals waiting to get their tickets and go through TSA. Passengers were allowed to enter the TSA checkpoint around 7:30 a.m.

More than 20 flights were delayed because of the power problems. Airport officials said losing utility power does not usually cause power loss to the entire terminal, and the matter is still under investigation.

The Connecticut Airport Authority worked with Eversource and Ameresco, which operates the cogeneration plant, to restore power.

“The CAA, along with Ameresco, continues to look at plant operations to determine why the plant did not provide power to the terminal facility (“island mode”) in the absence of utility power. The plant has operated in the island mode successfully many times in the past, with one of these occurrences taking place during Storm Alfred in 2011 when the plant operated for ten plus days without utility power. Our full investigation into yesterday’s incident is continuing, and we will continue meeting internally to compile and put into effect a series of recommended changes,” an airport spokesperson said in a statement.