Southwest Airlines flights were grounded nationwide. What we know.

Southwest Airlines departures all over the country were briefly halted on Tuesday due to a computer issue, causing significant disruptions at airports.

At a little after 11 a.m. ET, 36 percent of Southwest's flights were paused, according to Leslie Josephs of CNBC. The pause ended not long after it was announced, but flight delays continued.

As of this writing, many Southwest flights were still not departing on time. Jennie Runevitch, a reporter for the local NBC affiliate in Indianapolis, noted that the departure board at her local airport showed that "most" Southwest flights were delayed by roughly an hour. The board in her photo, it should be noted, also showed some Southwest flights departing on time.

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Southwest's statement about the incident said the temporary delay was caused by "data connection issues resulting from a firewall failure." Southwest was plagued by similar delays over the holidays last year and earlier this year, which were at least partly caused by a glitch in its weather software.