Gov. Tim Walz on Thursday signed an executive order activating the Minnesota National Guard to help restore peace following days of furor over a video showing a white police officer holding his knee on the neck of a black man who died.

Minutes after the governor's announcement, local and federal officials said the investigation is ongoing and neither the FBI nor the Department of Justice is ready to press charges against any of the officers involved.

"The federal investigation will determine whether the actions by the involved former Minneapolis Police Department officers violated federal law," U.S. Attorney for the District of Minnesota Erica MacDonald and Rainer Drolshagen, the FBI special agent in charge of the Minneapolis field office, said in a joint statement Thursday.

The Minneapolis Police Department swiftly fired the four police officers shown in the disturbing video, in which the arresting officer appears to shove Floyd's face into the pavement with his knee for at least seven minutes on Monday evening.

"The actions I watched in the video were incredibly disturbing and go against the basic law enforcement principle of preservation of life," he said, also acknowledging that the Los Angeles Police Department "has had our own high-profile incidents."