SOUTH BEND — 1st Source Bank is sending out letters reminding their customers to check their recent bank account activity. The bank says someone hacked into a computer containing debit card information earlier this month.

1st Source Bank says it doesn't know how many accounts the hacker got information on. But the bank doesn't think any money or personnel information was taken.

Many customers are still taking a closer look at their debit card activity.

"My main worry is that my money is going to be gone tomorrow when I got to my account," said Jeremy Reinke, a 1st Source Bank customer.

"Is my money still in my account, and can they correct this so it doesn't happen again?" asked Chris Stump, another customer who hadn't heard about the May 12 security breach. "I guess in some ways I would have liked to know by now."

1st Source Bank says it immediately reported the incident.

"We are working with law enforcement to find these bad guys, and we didn't want to tip them off," said James Seitz, senior vice president of consumer and electronic banking at 1st Source Bank.

The bank is now sending letters explaining what happened.

"The server that holds our debit card information they were in there and they transferred information out. But we can't really tell if it was 10, 20, or 30 percent of our card holders," said Seitz.

1st Source Bank says a special forensics team is going to take a look at the system.

New debit cards will be sent to all their customers even though the bank insists no personal information was taken.

"Our number one priority is our customers. We shut everything down right away and hired the best people we could get our hands on to see what happened here and to make sure it doesn't happen again," said Seitz.

But many customers still keep a closer eye on their accounts.

"We would pay a little more attention at least until they can figure it out," said Reinke.

1st Source Bank says customers should expect to receive a letter in the mail any day.

The debit cards shouldn't arrive until the second week in June, and current ones can be used until then.

The bank says you should take a look at your statements and report any fraudulent activity.

1st Source says its security meets or exceeds banking standards, but it plans to add more safeguards.