Initially, according to an early press release from the St. Augustine Police Department (HT 75NatChamps), former UCLA running back (and one of my favorite Bruins) was charged with misdemeanor battery in connection to a bar fight/incident at a bar/restaurant.
However, it appears the initial information was incorrect, with SAPD now stating that they took a statement/complaint against MJD for misdemeanor battery "stemming from an altercation" at a local bar/restaurant, but that MJD has not been charged with a crime and is "cooperating fully with [SAPD's] investigation."
At this time, it appears that there was a fight of some sort, where the bar/restaurant security got involved. Apparently, at least one individual has claimed that MJD struck him or her, but at this point, MJD is presumed innocent and the facts are simply allegations.
While troubling if true, at this point, UCLA and MJD fans can only sit-and-wait to see how the facts develop as SAPD investigate.