Six people were killed and many others were hurt in back-to-back shootings in Detroit, Houston.
James White, the chief of the Detroit police department, told the media that the first three victims were found with multiple gunshot wounds in different places early in the morning.
White said that the shootings don't seem to be planned.
Mayor Mike Duggan said that "many agencies" are looking for the suspect in "several square miles." "This person has already shot four people today," he said, calling for witnesses.
In Houston, Texas, a person with a gun shot and killed three people after setting their house on fire.
Troy Finner said that the gunman being kicked out "may have been a trigger point," but police are still looking into it.
The Washington Commanders RB Brian Robinson was shot in a possible robbery attempt and was hospitalised with non-life-threatening injuries.
The United States is frequently rocked by shootings, and policymakers are reluctant to implement gun control measures, despite it being popular with most Americans.