White-Hot Evidence of Demolition
NIST describes a "bright white" flame in World Trade Center 2 (the South Tower) shortly before it collapsed:
An unusual flame is visible within this fire. In the upper photograph in Figure 9-44 a very bright WHITE flame, as opposed to the typical yellow or orange surrounding flames, which is generating a plume of white smoke, stands out. The intensity of this flame is considerably brigther than normal flames.