The gunman, 50-year-old Paul Warren Pardus, had been listening to the surgeon around midday when he "became emotionally distraught and reacted ... and was overwhelmed by the news of his mother's condition," Police Commissioner Frederick H. Bealefeld III said.
Pardus pulled a semiautomatic gun from his waistband and shot the doctor once, the commissioner said. The doctor, identified by colleagues as orthopedic surgeon David B. Cohen, collapsed outside the eighth-floor room where Pardus' mother, Jean Davis, was being treated.
Pardus then holed up in the room in a more than two-hour standoff that led authorities to lock down a small section of the Nelson Building while allowing the rest of the sprawling red-brick medical complex — a cluster of hospital, research and education buildings — to remain open.
When officers made their way to the room, they found Pardus and his mother shot to death, he on the floor, she in her bed.