(CNN) — Cash registers at Target stores are back online — after a two-hour systems outage Saturday.

The outage left shoppers venting frustrations online — but also commending workers for efforts to diffuse tension amid long lines.

Target said guests were “unable to make purchases” at its stores.

Meanwhile, shoppers took to social media to complain that registers weren’t working at dozens of stores across the U.S. and posted images of long lines.

But at a Target in Brentwood, Tennessee, a shopper said customers were in good spirits and workers passed out coffee samples.

Workers there hand-entered bar code numbers — and customers cheered each time someone got checked out.

Some customers posted on Twitter that workers helped entertain kids and offered refreshments.

Target said the failure was not from a data breach or security-related issue, but from an internal technology issue and no customer data was compromised.

Target said, “Our technology team worked quickly to identify and fix the issue, and we apologize for the inconvenience and frustration this caused for our guests.”

It’s unclear how many Target locations were impacted.

The company has 1,800 stores in the U.S. and a presence in India.