RALEIGH, N.C. — An investigation at the Wake County Schools' Transportation Department has led to the resignations of three long-term employees.

Carol Finch, an 18-year veteran of the school system and a budget technology analyst; Pam Stewart, an 11-year veteran who is a team leader; and Angela Malloy-Sanders, a 17-year veteran, quality control manager, have resigned within the past 24 hours.

In a statement released Wednesday, the school system said it has serious concerns about a vendor's sale of certain parts, equipment and supplies to the Transportation Department. The statement does not identify the vendor, but says that the school system will determine if the vendor owes money.

The case was reported to the district attorney's office. Wake County District Attorney Colon Willoughby said the questions were raised from within the department.

"In an internal review, the school system developed information that appeared to be irregularities in their purchasing of goods," he said.

Officials with the State Bureau of Investigation are also looking into the situation. Willoughby said that is an important move regarding the parties in the case.

"In this situation, it involves a school system, a public entity and public money. Given the size of the school system's operation, it just seemed that the SBI was the appropriate agency to undertake it," Willoughby said.

Despite the investigation, school officials said there will be no problems regarding the transportation of students.