PASADENA (CBSLA.com) — An unsettling bug caused worry Monday night when Chase Bank customers accessed their online accounts only to see their checking accounts empty.

Chase says it has fixed the problem and assured customers that the issue was the result of a bug, and not a hack.

Many customers also experienced the problem of being unable to log on, seeing a “system unavailable” message. Those who were able to log on saw a depleted balance on their checking accounts.

The problem did not seem to affect ATM machines.

The scare prompted a large number of customers to voice their frustration over Twitter. Chase responded with a statement, trying to put their customers at ease.

“It has nothing to do with cyber threats or hacks,” the statement read. “It is an internal issue. We are very sorry to our customers for the inconvenience.”

Chase support tweeted at approximately 7:30 p.m. that the problem was fixed.