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ST. LOUIS, MO (KTVI) – If you were planning to fly out of or have visitors flying in to Lambert-St. Louis International Airport Sunday afternoon, you needed to check the status of that flight. The airport’s Terminal 1 experienced a significant power outage due to a blown transformer.

Terminal 1 houses flights from American, Delta, United, and Alaska airlines among others.

Ameren Missouri says the power outage was caused by rain water getting into insulators at the Lambert electrical substation damaging equipment.  That equipment was isolated and repaired.

Jeff Lea, a spokesperson for Lambert said the power outage affected 10 flights that had to be cancelled, with four to five hundred passengers from other carriers having flight delays of up to four hours.

Around 6 pm power was restored to Terminal 1.