Abstract: An extreme wind disaster occurred in Nanchang, Jiangxi Province, in the early morning of March 31, 2024, which caused the fall of three residents from a high-rise building. The fine structure of the severe storm near the accident building was investigated, primarily based on SA dual-polarization Doppler weather radar observations from Nanchang and intensive surface observations. The results revealed that a bookend vortex was embedded in the northern end of a bow echo of a quasi-linear convective system around the time of the accident, with its horizontal scale and vertical vorticity comparable with those of a strong mesocyclone. Tornado vortex signatures (TVS) with tornado debris signatures (TDS) on a smaller scale were identified within the bookend vortex, which passed over the accident building. The radial velocity difference of TVS exceeded 40 m·s⁻¹. Damage surveys conducted along the tornado path identified by TVS and TDS revealed multiple tornadic damages, including strong cyclonic rotational winds, localized convergent rotational winds, debarked trees, and completely collapsed stone bridges. This indicated that an EF2 tornado occurred very close to the accident building, which was most likely responsible for the fatal fall. Notably, the tornado-related vortices comprise a bookend vortex and several leading-edge misocyclones embedded within it, which emerged and intensified almost simultaneously during the wind disaster. The observational study on the formation mechanisms of tornado-related vortices indicated that they resulted from the tilting of the horizontal vorticity, which is associated with the strong low-level vertical shear of the elevated rear-inflow jet and baroclinic vorticity related to the gust front.