Police have not said what the man's motive was. Over the years, parents have made headlines across the country for killing their children.

On Tuesday, a New Jersey father killed his two children, then himself. In September, a man killed his estranged wife and step children in Florida.

In Kansas back in 1994, a man killed his two daughters at El Dorado Lake. Rick Follin said he killed his two daughters because he didn't want to lose them -- because he thought his wife would take them instead.

"We all have trouble understanding why anyone would hurt a child," said Dr. Russell Scheffer Wednesday afternoon. He is the chair of the KU School of Medicine's Psychiatry and Behavioral Sciences Program in Wichita.

In Liberal this week, police say a man tried to hurt three children. Friends say the man is their father.
    
"Fortunately, it's not common meaning every day, all the time," said Dr. Scheffer. "In comparison to other crimes, it's not dramatically uncommon either. It does happen, unfortunately."

Dr. Scheffer has seen a lot of child abuse cases in his more than 20 years in Psychiatry. But those that involve a parent killing a child share certain characteristics.

"It's much more common for males to take that injury -- 'I'm going to kill you so no one else can have you' (mentality)" he said.

Dr. Scheffer says women will also kill their children -- usually because the woman wants to kill herself, and doesn't want to leave her children alone.

He says if drugs are involved -- that heighten a person's actions. So instead of hurting a child, the parent could kill them.

Dr. Scheffer also says a divorce, or the end of a relationship, is the most common and most influential trigger, because it hurts a person's self-esteem.