Mass student-led protests calling for tighter gun control are underway across the United States.
The protests – under the banner March For Our Lives – have grown out of a movement calling for change after 17 people were killed by a gunman at a high school in Florida last month.
Half a million people are expected to descend on the biggest march in Washington DC.
More than 800 sister protests are planned nationwide and abroad.
Solidarity marches have taken place in London, Edinburgh, Geneva, Sydney and Tokyo.
Participants want to seize on public outrage in the wake of the 14 February massacre at Marjory Stoneman Douglas High School in Parkland to convince US politicians to finally take decisive action, including by banning the sale of assault weapons.
However, the issue divides Americans. The right to bear arms is protected under the 2nd amendment of the US constitution and the National Rifle Association (NRA) gun lobby remains highly influential.