The Los Angeles Rams said they will handle any discipline for the players involved in the brawl.
"The incident will be addressed internally and any discipline will remain in-house," a Rams spokesman said when asked if Donald would be disciplined.
After the first day of joint practices took place without any issues, Thursday's practice ended early after a fight broke out on the field.
A Cincinnati Enquirer photographer saw Donald holding a helmet in each hand. Donald was seen swinging a helmet multiple times during the scrum in a video that was posted on the social networking site.
Donald was not available to speak. He didn't say anything through a team spokesman.
In his post-practice availability, Rams coach Sean McVay said he didn't want to make a big deal of the fight and that no one was hurt.