The mid-afternoon beating by four teens of a Starbucks manager who died Wednesday on the SEPTA concourse at 13th and Market Streets is a reminder that violence can happen anywhere at any time.

That holds true even in a downtown widely regarded to be safe by commuters, residents and visitors. Nearly three-quarters of people surveyed by the Center City District say they are not fearful when downtown - and that confidence is borne out by statistics on crime showing a substantial reduction across Center City in the last decade.

Of course, the grieving family, friends and coworkers of Sean Patrick Conroy, the 36-year-old victim from South Philadelphia, won't find the solace they need in such statistics. The recently engaged Conroy was described as a gentle man who was attacked, police said, "for no reason whatsoever."

With one 16-year-old in custody, police were seeking three other Simon Gratz High School students suspected in the 2:35 p.m. attack. Police said the four had skipped school, and ambushed their victim for kicks without any thought of even robbing him.

The crime certainly fits into the category of what Mayor Nutter, in lamenting Conroy's death, described as "random, stupid acts of violence." As such, the hope is that it does not portend a trend.

While random and stupid, it was not wholly unexpected. Both SEPTA and city police have been coping of late with trouble-making teens on and around the subway system. Most of the incidents involved teens preying on other teens. Though there have been fights, most of the incidents have been minor and were resolved quickly.

Indeed, SEPTA officials yesterday noted that they had added plainclothes officers some time ago to work the transit concourses, and have been coordinating crime-prevention efforts with city police.

One measure of those tactics' success is the fact that a SEPTA police sergeant actually observed the beating of Conroy, who died from an asthma attack. The officer just wasn't close enough to stop the four teens seen beating Conroy as he waited at the Market-Frankford El stop.

However, the incident puts transit and city police on notice to review deployment. The goal should be to achieve a police presence that might further deter such young thugs. The results of an inquiry planned by City Controller Alan Butkovitz into the incident could prove useful.

Then, police authorities need to alert - and reassure - the public about the safety steps being taken.