Victims of gun violence, students and families march in Washington and communities around the country in a demonstration to end mass shootings in schools.
"Every single voice comes together and makes a huge impact. This is just the beginning. This march is the first step in a long process."
Britain is investigating whether Facebook, the world's largest social media network, did enough to protect data.
"These are the students that we were waiting for," said one advocate whose mother survived the shooting at Sandy Hook.
"France will never forget his heroism, bravery and sacrifice," the country's interior minister said.