Ground personnel reported during pushback the tow bar disconnected from aircraft unexpectedly and the aircraft rolled toward them. Captain set brakes to stop roll.

Narrative

The pushback driver could not see and could not park the plane straight. when it was time to disconnect the towbar would not release from the landing gear. I went to help him by taking over the push. I started to adjust he plane just fine and all of a sudden with the plane started to straighten out the towbar came loose and disconnected from the aircraft. I told the Captain to apply the brakes and all of a sudden; I saw the plane rolling towards me. Once I noticed the planes movement I called the Captain again to apply the brakes. It happened so quick I saw the plane keep rolling and the towbar went under the landing gear. At that point the Captain was able to set the brakes. I contacted the Ramp Manager; Aircraft maintenance and GSE (Ground Support Equipment) to ensure everything was fine. Everything looked fine. After discussing it with the Manager we thought it was best for the aircraft to return to the gate to get checked.I realized it happened as the towbar dropped on the ground.I'm not exactly sure why the event occurred but I went to help to try to fix the problem. Somehow the towbar became disconnected when there was no more pressure on the towbar. I called Management right away. I contacted to locate the Ramp Manager to have them come to the gate for assistance.