It happened on the 700 block of East Locust Avenue around 2 p.m. on June 22, city police told Daily Voice.
The 12-year-old was shot multiple times in the back, while a 30-year-old man and a 47-year-old man were each shot multiple times in the chest, authorities said.
Police rushed the trio to Einstein Medical Center where each was pronounced dead at 2:14 p.m., the department said.
No weapons were recovered at the scene and no arrest had been made as of Thursday evening, per police.
Anyone with information is asked to call 215-686-8477.
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