Power has been fully restored to Sydney Airport’s Terminal 2 domestic terminal after a failure in a power substation caused chaos for operators and disrupted travel for hundreds of passengers for about four hours Friday morning.

The substation, which supplied essential power services to Terminal 2, was unable to pass on its demand to backup supplies meaning all electronic check-in, service and air conditioning services were completely disabled. Only advertising screens with their own backup power still operated.

The outage affected T2 airlines Jetstar, Tigerair Australia and Virgin Australia, resulting in dozens of cancellations and a backup of passengers who had been unable to board.

According to an airport statement posted at 12:57 local time a.m. on Friday, “Power has now been fully restored at Sydney Airport T2 Domestic terminal. Security screening has recommenced and airlines are operating check-in counters and facilities. We are working to move passengers through the terminal as quickly as possible.”