Alaska Airlines flights were back late Sunday night after an IT outage forced the company to ground all flights for three hours. From 8 p.m. until 11 p.m. PST, Alaska Airlines planes were on hold. The airline did not reveal the nature of the outage.

Alaska Airlines flights resumed after a ground stop, but passengers can expect delays. See how many Phoenix Sky Harbor Airport flights are affected.

Alaska Airlines grounded its fleet late Sunday following an IT outage, before resuming operations early Monday.