Grassley: Gov't needs to do better on mental health and guns

"It seems to be common for a lot of these shootings, in fact almost all of the shootings, is the mental state of the people, Grassley told reporters. "And we have not done a very good job of making sure that people that have mental reasons for not being able to handle a gun getting their name into the FBI files and we need to concentrate on that."

Kamala Harris, a Democrat on the Judiciary Committee, urged people to look at autopsy photographs.

"When you see the effect on this extreme violence on a human body, and especially the body of a child, maybe it will shock some people into understanding that this cannot be a political issue," she told reporters. She said Congress must be practical, saying that while she supports the second amendment, the United States must have smart gun safety laws.

President Donald Trump tweeted on the mental health of the shooter on Thursday. "So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!"

The Florida school shooting is among the 10 deadliest mass shootings in modern US history.