GREENVILLE, S.C. -- Four officers have resigned from the Greenville Police Department as the federal government investigates the department.

Chief Terri Wilfong said that inappropriate and possibly criminal behavior from the four officers was brought to her attention. She said that because this in an ongoing investigation, and more details as to what happened cannot be released.

Wilfong did say that the incident happened two to three months ago and did not involve any serious physical harm or citizen complaints.

"Internally we found something that we thought didn't look right, so, an investigation began," Wilfong said. "They came to me and said, 'There is a problem and possibly a criminal element.'"

Wilfong said that after she called the State Law Enforcement Division in to investigate, officials with the agency said they wanted to contact the U.S. Department Of Justice, the solicitor's office, and the U.S. Attorney's Office.

The Department Of Justice is heading the investigation. Details of that investigation were not released.