(NEXSTAR) – Southwest Airlines has blamed “data connection issues resulting from a firewall failure” for interrupting the carrier’s nationwide operations on Tuesday morning.

Operations have since resumed, the airline said.

“Early this morning, a vendor-supplied firewall went down and connection to some operational data was unexpectedly lost. Southwest Teams worked quickly to minimize flight disruptions,” a representative for Southwest wrote, in part, in a statement shared with Nexstar.

“We ask that travelers use Southwest.com to check flight status or visit a Southwest Airlines Customer Service Agent at the airport for assistance with travel needs.”

Southwest’s statements came hours after customers complained of delays, claiming to have been told of a “nationwide grounding” of Southwest’s aircraft.

A representative for Southwest Airlines responded to the initial complaints, blaming “intermittent technology issues” for interrupting flights.

“As a result of the intermittent technology issues that we experienced, we should hopefully be resuming our operation as soon as possible,” a representative for Southwest wrote in response to a Twitter user around 9 a.m. CT, along with an apology to customers. In an update posted less than an hour later, Southwest added that there was no “time frame” for when the issue would being resolved.

The Federal Aviation Administration announced the carrier’s service had resumed just after 10 a.m. CT, following an earlier request from Southwest the FAA “pause the airline’s departures.”

Amid the disruptions on Tuesday morning, passengers had taken to social media to share their own experiences with delays, including one traveler in Denver who claimed a gate agent spoke of a “system-wide issue” causing a nationwide ground stop, and another passenger whose pilot allegedly blamed the nationwide grounding on a “computer glitch.”

An anchor with Nexstar’s KXAN was also stuck on a plane preparing to depart from Austin amid the disruption.

“Currently stuck on a @SouthwestAir plane at @AUStinAirport. @KXAN_News confirms Southwest told AUS just before 9 am about system-wide technology malfunction,” wrote Tom Miller, a morning KXAN anchor, on Twitter. “Southwest did not give a reason. Southwest Airlines tells AUS it is delaying flights in and out of AUS.”