It wasn't exactly what Mary Jane Fullam was expecting at dinner Saturday before heading to the Philadelphia Orchestra's performance of Haydn's The Seasons.

The 69-year-old East Falls resident was dining with her brother and sister-in-law at the Continental Mid-town at 1801 Chestnut St. when a large contingent of teenage girls materialized and started banging on the restaurant's plate-glass windows, she said.

Then, walking to the Kimmel Center after dinner, they navigated teens walking six abreast, clogging every sidewalk corner, smacking store windows, pointing and laughing, according to the retired School District of Philadelphia art teacher.

"It's hard to believe some of this was not planned. It just seemed like a tremendous number of people involved. I didn't have a sense they were coming from a club, I had the sense that they just showed up and they're going to have their way," Fullam said.

She and her companions, from Berks County, were not harmed, she noted. Still, she said, the notion of visitors to Philadelphia encountering roving mobs "is a disservice, the opposite of attracting people to the city and making them think they can come to the city and enjoy themselves. It was very upsetting, it was a threatening situation."

In a news release Wednesday, the Police Department said detectives are actively investigating two assaults, one aggravated assault, and five robberies in connection with the flash mob. Victims' injuries included a large laceration to the back of the head, a broken nose, and bruises. Twenty unknown male and female juveniles seen on surveillance video released Wednesday are being sought as suspects, the release said.

Flash mobs, the phenomenon of teens running amok on city streets punching, shoving, and stampeding through frightened onlookers and stores, are not child's play. But the alleged participants often are charged as juveniles.

Such was the case with a pair of teens arrested Saturday night by SEPTA police after more than 100 youths converged in the 1700 block of Walnut Street before making their way to 15th and Market.

Arrested was a 15-year-old girl who allegedly punched and kicked a SEPTA police officer. The girl, from the 4000 block of L Street in Juniata Park, was charged with simple assault, resisting arrest, and related offenses. A 14-year-old boy from the 5700 block of Filbert Street in West Philadelphia, seen by police allegedly punching someone near 15th and Market, was charged with simple assault, resisting arrest, and related offenses.

SEPTA police arrested both teens, who were charged as juveniles, and released them by Sunday, said SEPTA spokesman Andrew Busch, who added that the officer who was attacked was not injured. Authorities did not release their names because they were charged as juveniles.

NBC10 reported that several teenagers entered Lazaro's Pizza, in the 1700 block of South Street, later that night. The pizzeria's owner said two of his delivery men were attacked and a pizza was stolen.

Busch disputed a section of Wednesday's news release by the Police Department that said two female teens had been arrested for assaulting two SEPTA officers. The 15-year-old girl was the only suspect charged with assaulting an officer, and only one officer was assaulted, Busch said.

It was not the first time so-called flash mobs had hit Center City. They have been reported as far back as 2009. Just last March, about 1,000 youths connected through social media converged around City Hall in an activity that Police Commissioner Richard Ross called "idiotic."

"I don't know why you would want to come down to Center City and act that way," Ross said at the time. "Just to be clear, I'm not indicting everyone that came, but nonetheless, enough of these young people came down there and wreaked havoc."

Saturday's gathering was not started by social media, but took place after a large number of teens left the Coda nightclub at 1712 Walnut St. after attending an anti-smoking event, according to First Deputy Managing Director Brian Abernathy.

Criminal defense attorney Lopez Thompson said he believes large gatherings of young people of color sometimes are misidentified as flash mobs and elicit harsh responses from police and business owners.

"I think that the criminal justice system isn't the proper place for a child who might have been downtown and a fight breaks out and they get caught up in it," he said.

Unless juveniles who participate in flash mobs commit violent felonies, they likely will avoid adult criminal prosecution, according to criminal defense lawyers.

That means their cases will be tried in Family Court, which does not have juries, and can be closed to the public at a judge's discretion. Offenses are considered "delinquent acts" rather than crimes, the accused are "adjudicated delinquent" rather than "found guilty," and sentences range from probation to placement in a residential facility for up to four years or until the offender turns 21.

"The impact that any crime has on the city is an important consideration for the District Attorney's Office to consider and for a judge to consider," said defense attorney George Yacoubian. "But what the decision-makers have to consider more than anything is the maturity level of the defendant. Juveniles just don't have the maturity level to make sound decisions. For that reason, the system has to be wary of charging juveniles as adults and exposing them to adult punishments."

Former Common Pleas Judge Benjamin Lerner was faced with just such a decision in 2014 when three teenage girls stood before him having been charged as adults by the District Attorney's Office for randomly attacking female Temple University students near the North Philadelphia campus. Two of the girls, ages 16 and 15, used their fists. The third girl, Zaria Estes, 15, used a brick to bash a student's face, breaking her jaw, and causing extensive damage to her teeth.

Lerner ruled that Estes should be tried as an adult, but moved her co-defendants' cases to Family Court. "As horrible, as disgraceful, as disgusting was the conduct of those other girls, when you pick up a deadly weapon, when you add that element, that's a whole different ballgame in my view than what those other girls were doing," Lerner told Estes, who stood less than five feet tall.

She eventually pleaded guilty to aggravated assault, conspiracy and possession of an instrument of crime, and was sentenced by another judge to 2½ to six years in state prison, followed by four years of probation.