A man who became distraught as he was being briefed on his mother's condition by a surgeon at Johns Hopkins Hospital pulled a gun and shot the doctor Thursday, then killed his mother and himself in her room at the world-famous medical center, police said.
The doctor, who was wounded in the abdomen, was expected to survive.
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.
Bealefeld said he did not know what the woman was being treated for at Hopkins, a world-class institution widely known for its cancer research and treatment. It is part of Johns Hopkins University, which has one of the foremost medical schools in the world.
Michelle Burrell, who works in a coffee shop in the hospital lobby, said she was told by employees who were on the floor where the doctor was shot that the gunman was angry with the doctor's treatment of his mother.
"It's crazy," she said.
Pardus was from Arlington, Va., and had a handgun permit in that state, police said. The gunman was initially identified as Warren Davis, but police later said that was an alias.
The wounded doctor, an assistant professor at the medical school, underwent surgery.
"The doctor will be OK," police spokesman Anthony Guglielmi said. "He's in the best place in the world -- at Johns Hopkins Hospital."
With more than 30,000 employees, the Johns Hopkins medical system is Baltimore's biggest private employer. The hospital has more than 1,000 beds and more than 1,700 full-time doctors.
The Nelson Building is the main hospital tower. The eighth floor is home to orthopedic, spine, trauma and thoracic services.
Hopkins said it informed its employees about the gunman in an e-mail at 11:30 a.m., about a half-hour after the doctor was shot. They were told to remain in their offices or rooms with the doors locked and to stay away from the windows. At 1:30 p.m., another e-mail went out advising employees that police "are in control of the situation."
As the standoff dragged on, people with appointments in other parts of the hospital were encouraged to keep them.
Hannah Murtaugh, 25, a first-year student at the nursing school, said her physiology class in an adjacent building was put on lockdown. She said a classmate received a text-message warning from the school about a gunman in the Nelson Building. Her professor interrupted the lecture to let students know.
"They just kept telling us to stay away from the windows," she said. "I was scared -- wondering if any of my friends or other students who had clinicals that day were on that floor, hoping the situation would be contained, trying to see what was going on while staying away from the windows."
She said security personnel helped keep everyone calm and made sure doors were locked.
Associated Press writers Ben Nuckols and Kathleen Miller in Baltimore and Medical Writer Marilynn Marchione in Milwaukee contributed to this report.