The electrical breakdown of a gas at radio frequencies in the HF band (f approximately 10 MHz) has been studied in some detail over a period of about ten cycles of the applied field immediately prior to and following a breakdown event. Discharge current and voltage are monitored as a function of time, together with the photon output from electronically excited species in the gas. The development of the discharge over the first few cycles of the applied field following the initiation of the discharge is determined by parameters such as overvoltage and the dynamic properties of the radio frequency generator. These two properties in particular control to a large extent the early breakdown phase.