In Orlando, Florida, at least 12 people were injured in a stampede on July Fourth after people mistook fireworks for gunfire and fled, causing a panic. Elsewhere, Philadelphia’s mayor says he’s worried about the security of crowds in large-scale gatherings, after two police officers were shot and injured during a Fourth of July fireworks show. This comes as new data from the Marshall Project show mass shootings have become more common — and more deadly — in the United States over the past five years.