Police said Malmgren was being held at the Cape May County Correctional Center with bail set at $50,000.
Bill Gaston, father of Lazicki and Farrahanne Gaston, said the three girls had been out on the road after buying ice cream and swinging in a park. They were headed home when the girls were killed.
The accident happened in front of the Green Creek Volunteer Fire Company just off Route 47.
"They actually called and said there were too many bugs and they were on their way home," Bill Gaston said.
Farrahanne Gaston somehow escaped injury.
"Physically, she's fine," her father said. "Mentally, she's asking herself questions like why she was able to get out of the way - why she lived and her sister and cousin didn't."
Dauber was in New Jersey visiting for the week. She lived with her parents and siblings near Pennypack Park, Gaston said. According to her Facebook page, she just graduated from Austin Meehan Middle School.
Last week, in updating her Facebook profile, Lazicki posted pictures of herself and Dauber standing back to back, smiling.
Bill Gaston said Lazicki had earned admission to Cape May County Technical High School. "She wanted to be a forensic scientist, criminal justice," he said, his voice cracking. "She was on her way to fulfill her dreams."
He described her as mature, smart, and social.
"She was so logical. If you talked to her on the phone for five minutes, you wouldn't believe she was only 15 years old."
Dauber "would always put a smile on your face, always had something nice to say," Bill Gaston said. "Didn't matter if she was having a bad day, she was just an adorable little girl."
Condolences poured in through the girls' Facebook pages on Wednesday - a fitting tribute, as Gaston said it was the main avenue of communication for Dauber and Lazicki.
"I guess it's much easier for them to type than it is to pick up a phone," he said.
Contact Jessica Parks at 215-854-2771 or firstname.lastname@example.org.
Staff writer Frank Kummer contributed to this article.