In the US, celebrations, parades and fireworks for American Independence Day-- marred, by gunfire. A Fourth of July so representative of this problem plaguing the country: Mass shootings. In Chicago, police chased and arrested a man they believe shot six people dead and wounded at least 20 during a parade. The 22-year-old is believed to have scaled a nearby building using a ladder in an alleyway, then started shooting at parade-goers with a high-powered rifle from the roof. The US has seen more than 300 mass shootings already this year. Yasmine El-Sabawi reports.