Shots rang out around 11:50 Saturday night along the 300 block of Washington Avenue.
Investigators say people were inside and outside the home celebrating when the shooting started.
3-year-old Shawn Hargrove was shot in the ankle. A pregnant neighbor, 30-year-old Jermaine Walker, was shot once in the left shoulder and a 34-year-old male suffered from a graze wound to the stomach.
"They were sitting here just chilling and bullets started flying and my grandson got hit and the person here got hit and she's pregnant," Shawn's grandmother Althea Williams said.
They were all sent to Thomas Jefferson University Hospital in stable condition.
Investigators have brought in a person of interest in the case, but there's no word on if that person is considered a suspect or if he's being arrested.
This is one of two incidents involving children injured by bullets overnight. Around two hours later, a 9-year-old was struck by gunfire in Hunting Park.