United Airlines issued a nationwide ground stop on Tuesday due to a "systemwide technology issue," a company spokesperson told Insider.

The issue was triggered by a software update that caused a widespread slowdown in United's technology systems, the spokesperson said.

All United flights were temporarily held at their departure airports for slightly over one hour. Airborne flights continued to their destinations as planned, the spokesperson said.

The ground stop began at approximately 12:30 p.m. EST, according to the FAA. The airline confirmed to Insider at 1:37 p.m. ET that it was investigating the issue. Flights resumed around 1:45 p.m. ET, the spokesperson said.

"We have identified a fix for the technology issue and flights have resumed," a spokesperson said. "We're working with impacted customers to help them reach their destinations as soon as possible.

Stranded passengers affected by the ground stop in Denver, San Francisco, Kansas City, Houston, Dallas, and Washington, D.C. posted on social media about their experiences, with one user writing they had been on the "tiniest hottest plane" all day.

California Rep. Eric Swalwell said on X, formerly Twitter, that he was on a cross-country United flight during the outage and was working "to get more information to my constituents on this ground stop and whether it reflects a cyber threat."