Charges against Dawn Snell, 42, of Lansdowne, were announced on Wednesday.
She was charged with aggravated assault and reckless driving.
She is being held on one million dollars cash bail.
"I'm sorry. It was an accident," Snell said through tears as she was lead away by police after her arraignment.
Upper Darby Police Superintendent Michael Chitwood said Snell was trying to get her daughter to 69th Street Station as she ran a stop light and swerved into oncoming traffic, striking the boys.
Snell's daughter would not appear on camera, but told Action News police are mistaken, and that the car revved out of control and her mother could not stop it.
"She didn't mean to do anything like that," Snell's daughter said. "They're saying she fled the scene like a crazy person. She's not."
A preliminary hearing is set for next week.
Two victims very seriously injured
Two boys remain in critical condition following the crash. 13-year-old Philmon Beyene remains on a respirator with head injuries at Children's Hospital. He is said to have bleeding on the brain.
A schoolmate, Jemel Brunswick, is suffering a lacerated pancreas. He has been transferred to the Hospital of the University of Pennsylvania.
The third boy, Tyler Lowery, is talking, and Action News has learned he is talking to detectives.
All three are 7th graders at Beverly Hills Middle School.
The children were out at the time because the school had early dismissal.
Boy knocked out of his shoes
The accident happened around 12:10 p.m. Tuesday on Marshall Road at Littlecroft Road in Upper Darby Township, Delaware County.
Chitwood said two boys were standing at a curb on Marshall Road waiting to cross a street. He says that's when Snell allegedly hit two boys, then kept going.
Chitwood says Snell then hit a third boy about 15 yards down the street.
Then, Chitwood said, Snell then hit a car, slamming it into a parked car, and eventually came to a stop more than 25 yards down the road.
One of the boys was knocked out of his shoes, through the parking lot of an Auto Zone, then he hit the store wall.
A second boy was tossed more than 30 feet up Marshall Road. The third boy was thrown to the ground.
Witnesses say Snell was hysterical when she finally stopped, repeatedly saying she "could not stop the car."
Talking about the accident on Wednesday, Chitwood said it was not accident, calling it "careless, reckless and criminal."