Weekend shootings in US leave 6 dead, dozens injured.

At least six people were killed and dozens injured in a series of shootings across the US over the weekend, including in suburban Chicago, Washington state, Pennsylvania, St. Louis, Southern California, and Baltimore. While none of the incidents fit the definition of a mass killing, the number of injured in most of the cases does match the widely accepted definition for mass shootings. Experts disagree over the cause of the increase in violence, with theories including the prevalence of guns in America and less aggressive police tactics.