DURHAM, N.C. — The Durham Police Department has launched an internal investigation into an alleged assault involving six off-duty Durham police officers outside a Raleigh bar.

The names of the officers involved in the alleged attack have not been released and it was not immediately clear if any of them had been disciplined. Two investigators, however, in the Duke lacrosse rape case -- Sgt. Mark Gottlieb and R.D. Clayton -- were temporarily placed on administrative duty on Friday, according to Durham City Manager Patrick Baker.

Baker, citing confidentiality rules involving personnel matters, however would not comment on why the two officers were placed on new assignments or whether the change was linked to the Raleigh assault investigation.

Durham police Chief Steven Chalmers in a statement released on Saturday, said the department is working with Raleigh police in a criminal investigation of the alleged incident, which happened late Thursday night outside Blinco's Sports Bar on Glenwood Avenue.

Rene Thomas, 29, told WRAL that racial slurs were exchanged in the bar's parking lot before a group of men surrounded him.

"I turned to my left and there's a big guy --probably about 5'10", at least 250 pounds," Thomas said. "He takes off his shirt and rushes me."

Thomas said someone threw a punch and missed, and someone else kicked him in the head.

"I heard someone say, 'He's not worth it. Let's get out of here,'" he said, adding that he was disappointed by the alleged actions of the officers.

"They were officers of the law," Thomas said. "They didn't identify themselves. It would have been as simple as saying, 'We're police officers...you need to go back to where you came from.'"

No criminal charges have been filed against any Durham officers.

"We have a strict code of conduct and we expect every member of our department to conduct themselves in a professional manner at all times," Chalmers said in Saturday's statement.

Durham police had no comment on the matter Sunday.