The crash happened around 11:00 p.m. Saturday on the 900 block of Anchor Street.
Police say, at the time of the incident the driver, 28-year-old Erika Williams, was on her way home from a barbecue in Kensington where she was involved in a dispute with a number of people.
According to authorities, Williams was traveling at a high rate of speed when a ball rolled into the street. Williams swerved, police say, and veered off the road.
The out of control car slammed into the steps where Janice Drevitt-Jones' daughter and grandchildren, a 5-year-old and 2-year-old, were sitting.
The family, from New Jersey, was at a birthday party on the block.
"It sounded like whole block exploded," Janice Drevitt-Jones said.
Witnesses described a brutal scene.
"Oh my gosh! I saw blood everywhere, the car was pulled up on the porch," said Karan Johnson.
Three people were trapped until neighbors shifted the car off the victims.
Witnesses say a crowd of people rushed to the scene and heroically freed the family trapped underneath.
"We started pulling the car down and pulling it with all our might, at least 100 of us pulled it down and pulled it down," neighbor Kia Williams said.
"We did not know the baby was under the car until we lifted the car up, that's when we found my niece underneath the car and I'm like 'oh my God, oh my God,'" the victims' aunt Jane Dreuitt-Bell said.
The right leg of 5-year-old Anya Mwagala, the most seriously injured, was shattered.
"She's still in critical condition at this point; she lost her right leg," Drevitt-Jones said.
Anya's leg was amputated at the knee.
Her little brother, 2-year-old Lemear , stopped breathing when a neighbor stepped in and used CPR.
"I rushed over there. The child wasn't breathing at all so I gave him mouth to mouth CPR and I carried him near the step to get air," neighbor Marquise said.
"He got [Lemear ] breathing. He and my youngest son didn't wait for an ambulance and took [Lemear ] directly by car to hospital," Drevitt-Jones said.
Lemear is expected to recover.
Their mother, 36-year-old Dwania Druitt, has been discharged but is staying at her childrens' bedside.
A family friend, 31-year-old Asheena Sutton, was injured as well and was scheduled to undergo surgery Monday to stop internal bleeding.
28-year-old Erika Williams of the 5500 block of Hillcreek Circle has been charged with four counts of Aggravated Assault While DUI, Criminal Mischief, Possessing an Instrument of Crime, DUI, Simple Assault and Recklessly Endangering Another Person.
Drevitt-Jones says the young woman was oddly detached amidst the chaos.
"She was calm and the words that she said to my daughter, my daughter repeated it back to me, 'I'm sorry I hit you.' She walked across the street and sat down on the step," Drevitt-Jones said.
Neighbors on the block say cars constantly speed down the street.
"They fly like it's the Indianapolis 500," said Larayna Lyons.
Lyons says she's been trying to get speed bumps and 'Children at Play' signs installed.
She says sadly it takes tragic accidents like this to prompt change.
Bail for Williams has been set at $40,000.