" It ' Startled ' him , Lyndon Johnson was to say ; it sounded like a " report or explosion , " and he did not know what it was . Others in the motorcade thought it was a backfire from one of the police motorcycles , or a firecracker someone in the crowd had set off , but John Connally , who had hunted all his life , knew in the instant that he heard it that it was a shot from a high - powered rifle .
Rufus Youngblood did not know what it was , but he saw ' not normal movements ' in the Presidential car ahead down the incline -- President Kennedy seemed to be tilting toward his left -- and in the Queen Mary immediately ahead of him , one of the agents was suddenly rising to his feet , with an automatic rifle in his hands . Whirling in his seat , Youngblood shouted -- in a ' voice I had never heard him ever use , ' Lady Bird says --- " GET DOWN !!!! ..... GET DOWN !!!! " and , grabbing Johnson's right shoulder , yanked him roughly down toward the floor in the center of the car , as he almost lept over the back of the front seat , and threw his body over the Vice President's Body , shouting again , " GET DOWN !!!! ..... GET DOWN !!!! " By the time , a matter of only eight seconds later , that the next two sharp reports had cracked out -- everyone knew what they were now -- Lyndon Johnson was down on the floor in the back seat of the car , curled over on his right side . The sudden , loud , sharp sound , the hand suddenly grabbing his shoulder and pulling him down -- now he was on the floor , his face on the floor , with the weight of a big man on top of him , pressing him down ; Lyndon Johnson would never forget " his knees in my back and his elbows in my back . "

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