The sirens started sounding in Dresden at 21:51 (CET). Frederick Taylor writes that the Germans could see that a large enemy bomber formation—or what they called ""ein dicker Hund"" (lit: a fat dog, a "major thing")—was approaching somewhere in the east. At 21:39 the Reich Air Defence Leadership issued an enemy aircraft warning for Dresden, although at that point it was thought Leipzig might be the target. At 21:59 the Local Air Raid Leadership confirmed that the bombers were in the area of Dresden-Pirna. Taylor writes the city was largely undefended; a night fighter force of ten Messerschmitt Bf 110Gs at Klotzsche airfield was scrambled, but it took them half an hour to get into an attack position. At 22:03 the Local Air Raid Leadership issued the first definitive warning: "Warning! Warning! Warning! The lead aircraft of the major enemy bomber forces have changed course and are now approaching the city area". Some 10,000 fled to the great open space of the Grosse Garten, the magnificent royal park of Dresden, nearly one and a half square miles in all. Here they were caught by the second raid, which started without an air-raid warning, at 1:22 a.m. At 11:30 a.m., the third wave of bombers, the two hundred eleven American Flying Fortresses, began their attack.