The three deaths resulted from shootings on Thursday at Doctors Hospital in the city of Columbus. The shooter, Charles Johnston, 63, a retired teacher, claimed that his late mother had received poor medical treatment in the hospital, authorities said.
Johnston arrived at the hospital armed with three handguns and first fired at a male nurse he blamed for his mother's death, saying: "Do you remember me? Do you remember my mother?"
After that Johnston shot dead an administrative secretary as he was leaving the building. He then shot at a driver in the car park. The driver later died in hospital.
Johnston was then shot in the shoulder by a plainclothes detective.
In a separate incident on Thursday, a mother killed her two children in the U.S. state of Kentucky, and then went to the nearby university where she threatened a police officer with a gun, local police said.
Gail Lynn Coontz, 37, entered the University of Louisville she was attending on Thursday carrying a gun. After about a half-hour, officials managed to persuade her to hand over the weapon. No one was injured on campus, police said.
Coontz was arrested after giving her handgun to a health counselor. Police subsequently found the bodies of the single mother's two children, a girl aged 10 and a boy of 14, at her home. Police said they could have been shot in their sleep.
Shootings in academic facilities and other public places occur with alarming regularity in the United States. In April, the United States experienced its bloodiest mass shooting ever when an armed assailant killed at least 32 and wounded over 20 on the campus of the Virginia Polytechnic Institute before killing himself.
