(CNN) -- Aaron Hernandez -- already accused of first-degree murder -- was indicted Thursday on charges stemming from a jailhouse fight, a district attorney's office in Massachusetts said.
A grand jury in Bristol County on Thursday afternoon indicted Hernandez, 24, on charges of assault and battery tied to the February 25 altercation, according to a statement from that county's district attorney's office.
The former New England Patriots standout tight end also was indicted Thursday for threats to do bodily harm in connection with a November incident in which he allegedly threatened someone who worked at the jail.
Hernandez will be arraigned on these new indictments at a date yet to be set by the court, said the statement.
An attorney for Hernandez did not immediately respond Thursday to a CNN message. Attorneys have not responded to questions about the alleged February 25 fight involving an unidentified inmate.
Neither man was seriously injured in that altercation.
Bristol County Sheriff Thomas Hodgson earlier told CNN that jail officials would look at how the two inmates came into contact, because "no more than one inmate is supposed to be out at a time" in the unit in which Hernandez is housed.
Hernandez is behind bars on a murder charge, to which he's pleaded not guilty.
Authorities have said that Hernandez and two other men picked up Odin Lloyd from his Boston apartment in a rental car shortly before Lloyd was found shot to death on June 17.
Surveillance cameras then captured the rental car leaving the crime scene and Hernandez carrying a gun as he returned to his home minutes later, according to authorities.
CNN's Rande Iaboni and Chris Boyette contributed to this report