I have seen what I suspect are the mentally ill blindly walking in front of traffic. Some are high on drugs as part of their addiction. 
The scary ones are those who are mentally ill or intoxicated while driving. These people sometimes mow down many people at once.
Although no one commented on this story, I submit this as evidence: "The Jeep’s driver, Brandi Lee Gonzales, 20, of Eugene, faces charges of manslaughter, intoxicated driving and hit-and-run driving. Police said both Gonzales and Jongeward fled the crash scene but were later captured in the area."
Disclaimer: He is innocent until proven guilty, so he may not be convicted.