Car dealerships across the country are being forced to use paper forms as the auto industry looks to recover from a cyberattack that caused mass outages last week.

The attack hit CDK Global Systems, a cloud-based software that runs all back-end financials and information on car sales, financing, repairs, maintenance, and more. The company serves an estimated 15,000 car dealerships across the country.

Ford and Kia noted in statements to Reuters that some operations have been affected.

The interfaces were reportedly hit with back-to-back cyberattacks that caused dealerships to begin shutting down operations as early as Wednesday around 2 a.m. EST.

Related: Mark Cuban Issues Warning After His Google Account Is Hacked

Per Bloomberg, the group that claimed responsibility for the attack (which is believed to be based in Eastern Europe) demanded tens of millions of dollars in ransom to cease the system hack ahead of the weekend, which CDK was reportedly willing to pay.

“In the interim, we are continuing to actively engage with our customers and provide them with alternate ways to conduct business,” CDK told Reuters.

The software company is also planning to run an internal investigation and is cooperating with authorities as it works towards the full restoration of its services nationwide.

Related: GM Taps Costco to Sell Chevrolet, Cadillac Electric Vehicles

The restoration was underway by Monday afternoon, though CDK said that it estimated that full restoration would take “days” and not weeks to complete. Still, it did not give an exact estimated timeline as to when dealerships would be able to resume business as usual.

CDK did not clarify exactly how many customers were still affected by the attack as of Monday afternoon.