No. 35 Squadron led the target marking and, thanks to the clear weather and H2S radar navigation, accuracy was good, with markers falling close to the aiming point. On 24 July, at approximately 00:57, the first bombing started by the RAF and lasted for almost an hour. The confusion caused to German radar kept losses of aircraft low. While some 40,000 firemen were available to tackle fires, control of their resources was damaged when the telephone exchange caught fire and rubble blocked the passage of fire engines through the city streets; fires were still burning three days later.