[EDITOR'S NOTE:  Charges against the defendants in this case were later dropped (see related story).]

By Paul Kurtz and Jericka Duncan

PHILADELPHIA (CBS) — As Philadelphia police continue to investigate a 12-year-old girl’s claim that she was raped by at least four boys inside a Southwest Philadelphia recreation center last night (see related story), city officials say there’s little that could have been done to prevent the crime.

“First of all, we are outraged, not only that it happened at one of our recreation site, that it happened at all,” said Philadelphia Parks and Recreation deputy commissioner Susan Slawson today.  She says upwards of 50 people were taking part in various activities on the first floor of  the Francis Myers Recreation Center last night, yet no one could see what horrors were taking place on a third-floor landing.

“We had three of our staff members here,” she notes.  “We had basketball going on, line dancing going on.  We had our computer room open.  We had kids out here in the sprinkler. This happened at 7:30!  We had a number of adults, even volunteers, here when this incident happened.”

Slawson called it a “crime of opportunity.”

“You can have 20 people in a site, if the opportunity presents itself, it’s going to happen,” explained Slawson.

And Everett Gillison, Mayor Nutter’s chief of staff (at right in photo), is challenging members of the community to step up.

“The way that we can show that this can’t happen again is if mothers talk to their sons, fathers talk to their daughters and say, ‘This thing can’t happen anymore.’ “