A cyber incident at data provider CDK Global, whose software is used at 15,000 auto dealers, hampered operations Wednesday at US and Canada dealerships, the company said.

“We are actively investigating a cyber incident,” CDK spokesperson Lisa Finney said in a statement shared with CNN. “Out of an abundance of caution and concern for our customers, we have shut down most of our systems and are working diligently to get everything up and running as quickly as possible.

CDK operates numerous different types of products car dealers use to handle things like keeping records of negotiated deals to scheduling and communicating about service. Not every dealer uses CDK’s products, and even those that do may not use them for everything, but it’s been a problem for many.

“We have customers coming in today who had deals saved in the system,” said Jeff Ramsey, an executive with Ourisman Auto Group, which is headquartered in Maryland.

To protect customer privacy, customer’s details aren’t written out on a piece of paper that’s just sitting on the desk anymore. Instead, information about deals and customer appointments is kept in a server that’s now impossible for his salespeople to access.

Ramsey said he understands, though, that CDK is doing what it feels it must to secure this sensitive data. But it’s a major hassle in the meantime and could cost his dealerships some business.

Customers who are delayed in closing a sale at one of his dealerships could just find a dealer nearby that’s not having these issues and buy a new vehicle there, instead.

It’s car buying season, so it’s a real concern. “We’re in the summer months,” he said. “This is where we need systems functioning.”

Ramsey and Brian Benstock, general manager of Paragon Honda and Paragon Acura in Long Island City, New York, both said they were continuing to do business and were selling cars in spite of the problems.