Officials in a key swing state launched an investigation Friday after discovering 2,500 voter registrations they suspect of being fraudulent.

Many of the registration forms were found to have incorrect addresses, false identification information, false names or names that didn’t match Social Security details, the elections officials in Pennsylvania’s Lancaster County said.

“It appears to be an organized effort,” said the county’s District Attorney Heather Adams. She did not identify any organizations believed to be connected to the suspected fraud.

The statement said the suspect forms were dropped off in two batches at the Board of Elections office recently.

The effort has ties back to a “paid canvassing” operation, reported Lancaster Online.

“The officials said one or two organizations that conducted registration drives in the county in recent months were responsible for the applications. They did not name the organizations,” said the report.

Some of the registrations were legitimate, with about 60% having problems, said Adams.

“Individuals listed on the applications informed detectives that they did not request the form, they did not complete the form, and verified that the signature on the form was not theirs,” Adams said.

She said most of the forms were dated Aug. 15 and after.