United Airlines lifted the ground stop of its domestic flights that was issued Sunday evening, according to the airline's Twitter account. 

United had initially grounded all domestic flights Sunday around 7 p.m. due to an IT issue.

"We’re working on a resolution. We apologize for the inconvenience," the airline tweeted at 7:06 p.m. 

Travelers replied to United via Twitter and asked about searching for alternative flights and if the issue affects planes currently in the air and United representatives said that it isn't affecting them.