An indicator buoy was released and smoke candle fired. By 16:00, "Grebe Cock" was becoming concerned for the safety of "Thetis" and radioed HMS "Dolphin" submarine base at Gosport. A search was immediately instigated. Although the stern remained on the surface, only three RN personnel (Lieutenant Frederick Woods, Captain Harry Oram and Leading Stoker Walter Arnold) and one Cammell Laird man (Fitter Frank Shaw) escaped before the rest were overcome by carbon dioxide poisoning caused by the crowded conditions, the increased atmospheric pressure and a delay of 20 hours before the evacuation started. Ninety-nine lives were lost in the incident: 51 crew members, 26 Cammell Laird employees, 8 other naval officers, 7 Admiralty overseeing officers, 4 Vickers-Armstrong employees, 2 caterers and a Mersey pilot. The crew waited before abandoning the vessel until she had been discovered by the destroyer , which had been sent to search for her and which indicated her presence by dropping small explosive charges into the water.