Duncan tells reporters that schools are often the safest place in a community, and gun violence is a societal problem and "not a school problem."
He says tougher gun control measures are needed. A spokeswoman for Duncan clarifies that he means the problem isn't a lack of school safety, but easy access to guns.
Recent school shootings in New Mexico and Philadelphia combined left four students wounded.
Duncan says it's also important for schools to focus on providing mental health resources.