NORMAN, Okla. (AP) — Two University of Oklahoma students have voluntarily withdrawn from the school after one appeared in a video posted on social media wearing black face paint and using a racial epithet, the university's president said Monday.

The Rev. Jim Gallogly said the two women apologized for what he called a "shocking, racist video" and that they appeared taken aback by the backlash after the video appeared on Twitter Friday.

"Those students will not return to campus. This type of behavior is not welcome here and is condemned in the strongest terms by me, and by our university," Gallogly said at a news conference, noting that Monday is Martin Luther King, Jr. Day, in celebration of the slain black civil rights leader.

"I ask you to hold his ideals high as we work toward a more inclusive and caring future for our university," Gallogly said.

He said the university is investigating whether a third student was involved in the video.

Since the video surfaced, the OU Black Student Association has called for a zero-tolerance policy on hate speech, more social and cultural classes, more multicultural faculty and staff, and additional financial assistance for African-Americans at the school in Norman, Oklahoma. The association has yet to respond to Gallogly's announcement.

OU severed ties with a fraternity and expelled two students in 2015 after several members took part in a racist chant caught on video that referenced lynching.

"Obviously we've had a second incident in several years. These kinds of things are totally unacceptable to our community. It shows that there must be something systemic. We have work to do," Gallogly said.

The Black Student Association has announced an on-campus "Rally to Stop Racism" on Tuesday. Gallogly said he has accepted an invitation to address students at the rally.