Fights broke out Wednesday afternoon in Center City where about 500 youths packed Dilworth Park, according to reports.
According to Metro, a police source called the swarm of young people a "perfect storm" and believe the warm temperatures and social media led to the huge crowds.
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Dave Schratwieser of FOX29 reports, at least, five teenagers were arrested as a result of the altercations.
SEPTA Police Chief Thomas Nestel, who was in Center City on Wednesday, said on Twitter the city's youths were "off the hook," subsequently clarifying that a small number were "out of control" and making other young people look bad.
Police have been combatting frequent violence between students at the transportation corridor at 15th Street in Center City.
Additional plainclothes officers, who are trained to look for signs that lead to violence, have been sent to ride subways and officers are keeping a closer eye on students at SEPTA stations during after-school hours.
Nestel has said that the situations they've been handling tend to get out of control when large groups gather and that the incidents tend to be fueled by social media.