A federal grand jury has indicted four former Minneapolis police officers in connection with the death of George Floyd, alleging the officers violated Floyd's constitutional rights, according to court documents filed in federal court in Minnesota.

The indictment says Derek Chauvin -- who was convicted last month on state murder charges in the Black man's death -- deprived Floyd of the right to be free from "unreasonable seizure, which includes the right to be free from the use of unreasonable force by a police officer."

Tou Thao and J. Alexander Kueng were also charged in connection with their failure to intervene in Chauvin's use of unreasonable force, per the indictment. Chauvin, Thao, Kueng and the fourth officer, Thomas Lane, all face a charge for failing to give Floyd medical aid.

According to the indictment, "the defendants saw George Floyd lying on the ground in clear need of medical care, and willfully failed to aid Floyd, thereby acting with deliberate indifference to a substantial risk of harm to Floyd."

Chauvin was also charged in a separate indictment related to an incident in which he allegedly used unreasonable force on a Minneapolis 14-year-old in September 2017, the Justice Department said in a statement Friday.

The first count of that indictment says Chauvin "held the teenager by the throat and struck the teenager multiple times in the head with a flashlight," per the DOJ statement. A second count says he "held his knee on the neck and the upper back of the teenager even after the teenager was lying prone, handcuffed, and unresisting, also resulting in bodily injury."

The federal charges are separate from the civil investigation into Minneapolis policing practices announced by Attorney General Merrick Garland last month, the Justice Department said.

Thao, Kueng and Lane also face state charges, including aiding and abetting second-degree murder and aiding and abetting second-degree manslaughter. They have pleaded not guilty, and their joint trial is expected to this summer.

The three former officers appeared with their attorneys in federal court Friday via video conference, and all three were released on $25,000 bond. Chauvin, who's awaiting sentencing on state convictions in June, remains in custody.

CNN has reached out to the Minneapolis Police Department and the city's police union for comment on the federal charges against the former officers.

The attorneys representing Floyd's family said in a statement that they are "encouraged by these charges and eager to see continued justice in this historic case that will impact Black citizens and all Americans for generations to come."

The statement from civil rights attorneys Ben Crump, Antonio Romanucci, and L. Chris Stewart said, "the additional indictment of Derek Chauvin shows a pattern and practice of behavior."

Minnesota Attorney General Keith Ellison, who led the state's prosecution against Chauvin, called the charges "entirely appropriate," saying the federal government had a "responsibility to protect the civil rights of every American and to pursue justice to the fullest extent of federal law."

News of the indictments were celebrated by civil rights leaders and activists like the Rev. Al Sharpton and the National Action Network, who said in a statement the charges show "we have a Justice Department that deals with police criminality and does not excuse it."

"For many years we have tried to get the federal government to make it clear that these crimes are not only state crimes but violate civil rights on a federal level when police engage in this kind of behavior," the statement said.

"What we couldn't get them to do in the case of Eric Garner, Michael Brown in Ferguson, and countless others, we are finally seeing them do today and this is a significant development for those of us who have been engaged in the struggle and police reform movement."