The incident happened in front of a Dollar Tree store in the Port Richmond section of Philadelphia on Monday evening.
"My heart is ripped out. I lost two of my best friends," said the victims' friend Tim Stewart.
There were teddy bears and candles arranged outside the store on the 3600 block of Aramingo Avenue on Tuesday in honor of the victims. They were described as homeless men in their 50s.
The 15-year-old student driver hit the men with an SUV around 8:45 p.m. Monday.
"She was navigating in the parking spot and the vehicle lurched forward striking two men," said Capt. Mark Overwise of the Accident Investigation Division.
Police say the girl was accompanied by her mother and two other people at the time of the crash in the high-traffic Aramingo Village shopping center parking lot.
No criminal charges have been filed as the investigation continues.
It's a heartbreaking tragedy for Stewart, who now sits without his friends.
"It was a misfortunate accident, but why should a 15-year-old girl be driving a car with her mother in the passenger side?" he said.
Criminal Defense Attorney James Funt says a number of factors will come into play when deciding liability.
"If they went out and stole the parent's car, drinking, joy ride, it's a different scenario," Funt said. "As I understand the facts, they were under parental supervision."
Funt said he thinks the mother would bear legal responsibility, as state law says drivers must be 16 years of age to obtain a permit.
"You need to have a learner's permit in order to legally be able to teach your child," he said.
The identities of the victims have not been released.