Live streaming is a tool terrorists use to spread messages of fear, whether they're radical right-wing extremists or members of ISIS, an expert says.

"This pattern held true even for physician groups that publicly endorsed evidence-based policies to reduce firearm injury."

Years lost from fatal gun injuries differ by race, research finds, which suggests interventions need to vary, as well.

Since 1999, about 4 of every 100,000 US children and teens have died by a gun-related homicide, suicide, or unintended shooting each year.

"As a physician and a researcher, I know that it doesn't have to be this way."