Two horrific mass shootings, in El Paso, Texas, and Dayton, Ohio, which left a total of at least 29 people dead and more injured, have again highlighted the need to reform US gun laws.

The attack at a Walmart in El Paso appears to have a sinister undertone. Police are investigating whether a white supremacist manifesto, posted anonymously online minutes before the shootings, is linked to the killer. Mexico is visible from the parking lot on a clear day. Thousands of Central American families have sought asylum in the city, which is home to generations of Mexican-Americans and seen as a symbol of integration.