Not everyone was pleased with Mayor Nutter's "sermon" Sunday on black youths and violence, but it's not hard to understand why. The mayor was on target in urging black youths and parents to act more responsibly, but his broad brush didn't make as clear a distinction as it should between who's been bad and who's good.

Nutter may be making the same mistake in emphasizing a stricter curfew as one tool to stop marauding gangs of teens from attacking and robbing anyone unlucky enough to be in the same place at the same time. Honors student or degenerate, if you're under 18 and it's after 9 p.m., don't be seen walking in Center City or University City. The obviously unintended message is that less affluent neighborhoods may have to put up with teens after dark, but their residents should know how to watch their backs. Right?

A curfew wouldn't have made a difference had it been in effect when the worst flash-mob attack occurred nearly two weeks ago in the early afternoon. Five randomly selected victims were beaten, with one ending up in the hospital with broken teeth and a wired jaw. Another violent flash mob did occur after 9 p.m. that day, this one including an 11-year-old boy seen trying to steal a man's bag. But spontaneous thuggish behavior can't be characterized as endemic to specific hours.

That isn't to say a curfew won't be useful, or that one shouldn't be employed. But it's important to remember that violence by disaffected youths can occur at anytime. It was afternoon when teenage predators jumped on other kids outside South Philadelphia High School.

Then as now, the proper deployment of police will have a much greater impact on making the streets anywhere safer. Recognizing that, Nutter and Commissioner Charles Ramsey have also announced plans to provide a stronger police presence where street violence has occurred.

The mayor also announced that 20 of the city's largest recreation centers will be open until 10 p.m. on Fridays and Saturdays, and other programs are being created to give young people alternatives to roaming the streets. The police and rec-center parts of Nutter's "holistic response" to flash mobs will likely have the most impact on preventing violence.

Not just teens, but others, didn't follow Nutter's reasoning at Mount Carmel Baptist Church when he said mob violence by black teens reflects badly on all African Americans. But evidence supports the mayor. Too often, stereotypes still dictate how blacks, particularly black males, are viewed by others. Violent acts by a few can be seen as justification for prejudice against all.