It would seem that in Ray Bradbury's Fahrenheit 451, by the time Mildred runs out of the house and into the taxi she has two concerns, both stemming from the same issue. Mildred has notified the authorities that her husband Guy (a fireman) has been collecting books. With this done, she knows that other fireman will be arriving to burn the house. This would be her initial reason to flee. The second reason may well be that Mildred does not want to run into her husband in that she has betrayed Guy. Even as Guy and his co-workers arrive, and Guy realizes she is responsible for the call that brought them there, he calls to her several times, but she continues to rush away. Mildred was very much brainwashed by society and turns him in rather than supporting her husband.