(Reuters) - A 4-year-old Pennsylvania girl surprised a driver and passengers when she boarded a public bus alone in the middle of the night on a quest for a sugary slushy, transportation officials said on Sunday.

Surveillance footage shows the pint-sized girl with blonde hair, bundled up in all purple, boarding a Philadelphia bus at 3 a.m. local time on Friday and sit down by herself as a handful of passengers look curiously toward her.

The girl, who appeared cheerful as she stretched and dangled her boots off of her seat, told bus riders that she wanted to get a slushie, Southeastern Pennsylvania Transportation Authority spokeswoman Kristin Geiger said.

Upon noticing the child, the bus driver pulled over, called his control center and waited for police to arrive, Geiger said. The girl was taken unharmed to a nearby hospital, where she was reunited with her parents.

Driver Harlan Jenifer, who Geiger described as an exemplary employee, told reporters that he was "shocked" to see the girl riding solo.

The parents of the girl said they did not know that their daughter had slipped out the back door in search of her favorite beverage at a nearby convenience store, the local ABC News-affiliate reported.

"I will take you to buy a slushie," mother Jaclyn Mager told her daughter, who asked again for the drink, in an interview with the local television station. "But ... promise me next time you'll wait for me, okay?"