Southwest Airlines (NYSE: LUV) on Wednesday reported earnings that topped analysts' estimates, but revenue was slightly lower than expected.

Shares of Southwest were more than 6 percent lower in premarket trading following the announcement.

The airline posted earnings excluding items of 93 cents a share on revenue of $5.139 billion.

Analysts polled by Reuters had expected Southwest to report earnings of 88 cents a share on revenue of $5.165 billion.

The airlines results were marred by a technical systems failure in July that caused flight delays.

"It was a solid quarter except for that tech outage," Gary Kelly, Southwest Airlines chairman and CEO, said in an interview on CNBC's "Squawk Box." "It's a very competitive environment out there, but really strong earnings and really strong returns on capital, so we're in a very strong position."

He added: "We're all benefiting from lower energy prices compared to levels that we had in 2013-2014 and some of those savings are being passed on to consumers. We still have real strong profits, still investing in the business, still growing. We're slowing our growth for next year to enable us to target hitting positive unit revenue growth."

More From CNBC

• Top News and Analysis
  

• Latest News Video
  

• Personal Finance