Only Red has started. Notice that the Race Committee boat is fly flag X-Ray, indicating individual recalls. Green was on the course side (OCS) before the starting signal and needs to return to the pre-start side of the line before starting. Blue is still behind the line and therefore has not started yet.
X-Ray (a white flag with a blue cross) is flown with a single sound signal to indicate a boat or boats were over the line early and must return to start properly. When a general recall flag is flown, it is accompanied by two sound signals.