Citadel President Lt. Gen. John W. Rosa called the Facebook post "offensive and disturbing" in a statement today and said that suspension proceedings had begun for the students involved in the photographs.
A woman, who was not a cadet, reportedly saw the image on Snapchat and then posted the screenshots on Facebook.
The social media posting "shows an upper class cadet in front of seven cadets with pillowcases over their heads," Rosa said.
"In accordance with college policy, we immediately began suspension proceedings ... and we are continuing to investigate this incident," he said. "We will provide more information upon completion of the investigation."
Rosa said that an initial probe had revealed the cadets were singing Christmas carols in a "Ghosts of Christmas Past" skit.
"These images are not consistent with our core values of honor, duty and respect," he said.
In a statement, Lamont Melvin, chairman of the Citadel Minority Alumni Association, called the social media posting "disgraceful."
"Regardless of the spin that one may try to assign to this type of behavior, the characterization of what took place was 'not a mistake' that can simply be swept under the rug. We are pleased that Lt. General Rosa and his staff have taken swift action to address the situation. ... We will continue to do our due diligence and await the results of the administration's investigation."
Thirteen students have been suspended, according to the Post and Courier in Charleston, South Carolina.