At least six killed, dozens injured in weekend shootings across US

At least six people including a Pennsylvania state trooper were killed and dozens injured in a string of weekend violence and mass shootings across the U.S.

The shootings in suburban Chicago, Washington state, Pennsylvania, St. Louis, Southern California and Baltimore follow a surge in homicides and other violence over the past several years that experts say accelerated during the coronavirus pandemic.

There's no question there's been a spike in violence, said Daniel Nagin, a professor of public policy and statistics at Carnegie Mellon University. Some of these cases seem to be just disputes, often among adolescents, and those disputes are played out with firearms, not with fists.

Researchers disagree over the cause of the increase. Theories include the possibility that violence is driven by the prevalence of guns in America, or by less aggressive police tactics or a decline in prosecutions for misdemeanor weapon offenses, Nagin said.

As of Sunday evening, none of the weekend event