An armed man strolls through a basketball game, opens fire on the bleachers, injuring six people, one critically. The shooter is still at large. Of the 500 people present at the game, not one has stepped forward with information that might help the police find the shooter.

This week's incident, at the Kingsessing Recreation Center, is a discouraging chapter in the city. We are as upset as anyone - including Mayor Nutter, who offered a $20,000 reward for information (215-686-TIPS) - over the irony of violence occurring in a so-called "safe haven" rec center. But the fact that the culture of "no snitching" is apparently still alive and well is also troubling. The collective silence makes the bystanders complicit in the injuries of innocent people.

But another announcement from Nutter's office suggests there may also be an alternative way to look at this.

Add a slight variation to the story: Imagine that of the 500 people at the game, 450 are illegal immigrants. Or 200 are. Or 50 are.

And imagine that no one has come forward for fear of deportation by flagging themselves in the system and inviting a visit from the U.S. Immigration and Customs Enforcement (ICE).

The city's currently allows ICE access to the names of people arrested under an arrangment set to expire soon. ICE does not have access to the names of victims and witnesses, but we can see how this arrangement, part of a "Secure Communities" program wherein local and federal law enforcement work hand in glove to identify deportation targets goes a long way to fostering both silence and a mistrust of police.

It would be nice if the immigration question would stay black or white: If we could either all agree that every illegal immigrant is bad and should be deported, or that all illegal immigrants are here for the kind of second chance that many of our own ancestors had in this "nation of immigrants" and deserve sanctuary. The reality, alas is not so black and white. Some illegal immigrants are violent criminals or those who want to harm our country, and some are here because being in their home country would mean being dead. It's hard to see how to accommodate both realities with a simplistic blanket policy.

Mayor Nutter and other officials grasped that dilemma when they negotiated the deal last year that would bar ICE access to names of witnesses and victims. As the city is set to renew its arrangement with ICE, it should consider further refinements.

After all, not all arrests lead to convictions. And traffic violations and misdemeanors are not as serious as violent crimes.

Councilwoman Maria Quinones-Sanchez proposes the city delay the time it allows ICE to access records, until after a preliminary hearing when it is clearer who might be a victim and who might be a defendant. This seems like a reasonable compromise to a tough issue.