'This is on their hands': Parkland teens call out lawmakers after Maryland school shooting
Sarah Chadwick, Sofie Whitney on MSNBC

Parkland teens reacted in horror to another school shooting -- this time in St. Mary's County, Maryland.

Many of the Florida students have become outspoken gun safety advocates after a gunman killed 17 of their classmates and teachers Feb. 14 at Marjory Stoneman Douglas High School, and they renewed their call for legislative action after a shooting Tuesday morning at Great Mills High School.