Sometime in the dark hours of a recent Sunday night, gunmen opened fire inside an illicit marijuana farm in Riverside County, killing seven people.

It was, according to data maintained by the Gun Violence Archive, the 28th mass shooting in California since the beginning of the year, part of a nationwide anomalous trend: While overall violent crime has edged downward this year, homicides have increased in several major cities, including in Los Angeles.

There also has been a spike in mass shootings (defined as single events in which least four people are wounded or killed) that began in the summer. At around 400 incidents, the number has already surpassed the annual totals in three of the last four years, according to an analysis by online news site the Trace.

Experts believe the pandemic has exacerbated the pre-existing social problems that feed violence in certain areas — the lack of jobs and educational opportunities, reduced access to mental health care and other services and, now, an overlay of social isolation that can bring simmering personal conflicts to a full boil.

Mass shootings often begin as domestic disputes, or confrontations among acquaintances. In fact, the Everytown for Gun Safety advocacy group reports that for the decade ending in 2018, six in 10 mass killings (defined as at least four people dead excluding the shooter) occurred in private homes.

Remedies must focus on those who turn to violence as a perceived solution, and that requires, among other tactics, providing programs in schools and other settings designed "to change gendered expectations for males that emphasize self-sufficiency, toughness, and violence, including gun violence."

Of course, there would not be mass shootings were it not for the presence of guns, and so far this year there also has been a surge in gun sales. Through the end of August, the Federal Bureau of Investigation processed nearly 26 million firearm background checks — a loose proxy for gun purchases — which is more than it processed in all of 2017. From 2017 to 2019 it averaged more than 2.2 million background checks a month. So far this year, the rate has jumped almost 50%.

Usually such leaps come when people fear that the government is poised to make it harder to buy guns, often after high-profile mass shootings at schools, churches or other public places. But according to a Brookings Institution report, a propelling factor this year is personal fear arising from the pandemic, augmented by reactions to political unrest and demands for defunding police in the wake of the police killing of George Floyd.

So partway through the pandemic, this is where the nation finds itself — with increased stress, a greater sense of personal isolation, elevated gun sales and less access to jobs and support systems apparently fueling more mass shootings. We can only hope that the pandemic will pass and that the stresses feeding this violence will fade away.

But then we'll still have the guns, and the structural racism, and a body politic that has proved incapable of taking the steps necessary to reduce access to firearms while increasing access to the jobs and social services the experts keep telling us are necessary to reduce gun violence.