Alaska Airlines warned of more flight disruptions on Monday after an unexpected failure of a critical piece of hardware at its data centers late Sunday forced it to halt all flights for about three hours.

Alaska Airlines canceled over 150 flights — including 64 on Monday — after a critical IT hardware failure forced a system-wide ground stop late Sunday. The issue, unrelated to any cybersecurity incident,

Alaska Airlines said its operations have resumed after a temporary ground stop was issued on all its flights and those of a regional subsidiary Horizon Air due to an IT outage affecting its operations,