A PROMISING team approach by Seattle, county and federal officials, Mayor Mike McGinn and law-enforcement officials, including U.S. Attorney Jenny Durkan and King County Prosecutor Dan Satterberg, is a welcome response to escalating gun violence.

Durkan's promise to prosecute more gun-violence crimes under federal firearms statutes — which carry longer prison sentences than state laws — is significant. Typically, federal prosecutors take up only the worst gun-crime cases. The change increases the chances that people who commit crimes eligible for federal prosecution and more prison time will get it. Locking up career criminals and armed felons has a strong chance of quelling gun violence on the streets.

Certain gun crimes have been selected for tougher federal prosecution for nearly a decade under a U.S. Department of Justice program called "Project Safe Neighborhoods." But Durkan expects her office to be more aggressive and the number of firearms cases selected to increase. Last year, 40 federal firearms cases were selected from about 200 cases reviewed. The public should keep count.

A second approach by the Seattle-King County-federal team is aimed at getting illegal guns off the street.

Police have recovered 361 guns since Jan. 1. Many were stolen in burglaries, car prowls and other types of thefts.

Message to the public: For Pete's sake, lock up your guns. It is not an infringement upon anyone's Second Amendment right to require responsible gun ownership, including keeping weapons locked away.

In addition to the plethora of stolen guns, gun owners ought to be persuaded by the heartbreaking Puget Sound-area stories of kids killed by guns they, a sibling or a friend found lying around.

Seattle's spike in gun violence — 21 homicides so far this year, one more than in all of last year — can be attributed largely to a disturbing culture of youth and gun violence.

But access to guns by people with mental illness is a glaringly unaddressed piece of the puzzle. The May 30 shootings by a mentally ill gunman that resulted in four deaths at a local coffee shop and a fifth person at a different location underscores a problem.

McGinn and Durkan are right that the mental-health issue is complex and possible solutions lie outside of the criminal-justice system. But they have laid the seeds for a successful partnership on a critical issue. That could serve as a model for finding the other pieces to the violent-crime puzzle.

This editorial originally referred to Project Safe Neighborhoods by the wrong name.