TMZ reports that the incident began just after Takeoff was asked to remove his bag sitting on the floor, and place it in the overhead bin. However, all three of the Migos' crew were asleep a the time and none responded to the flight attendant's request.
Shortly after they were asked to gather their things and disembark from the plane. Their manager threatened to sue Delta for the action, claiming it was racially motivated and not just a simple situation of a bag being places in the aisle (can someone even get kicked off a flight for that?)
Delta has yet to respond.
[Update: Delta Responds]
A Delta spokesman told TMZ that the flight returned to the gate because Migos repeatedly refused to follow the staff's instructions to buckle seatbelts and store carry-on's in overhead bins. Delta says it rebooked Migos on an alternate flight, which is already in the air, if not landed by now. We'll continue to keep you posted.