DALLAS (CBSDFW.COM) – A suspect in a string of car burglaries is in custody after Plano police say they caught him in the act of breaking into a car with a 5-year-old child inside.

Frankie Xu witnessed the crime from her car seat.

“A stranger came in our car,” the 5-year-old said.

Her mother, Kelly, said she had just loaded up the groceries in the parking lot of Costco in North Dallas.

“I put my purse down and started the car,” she said, “so that the car would warm up because it was freezing.”

All she had to do was return the cart.

“My back was to the car for, I don’t know, it was ten seconds or less,” she said.

She came back to find Frankie talking about a stranger and her car alerting her the keys were gone.

But, it wasn’t the missing purse that left her suddenly scared.

“It was horrifying honestly.” she said, thinking of how close the thief had come to her daughter. “My child was literally right there.”

Luckily, Plano police officers were also there.

“I remember thinking, ‘How did they get here this fast?’” she said.

The department says undercover officers were tailing 26-year-old Terren Flowers, a suspect in several car burglaries, when they saw him snatch the purse.

“He [the officer] was like, ‘Your daughter was completely protected,” Xu said.

Officers told Frankie her clear description of what happened helped solidify their case.

As a thank you, they gave her a Plano Police Department patch that she plans to add to the jean jacket she wears.

“I’m thinking about putting it right here,” she said, placing it so it will lie over her heart.

Plano police followed Flowers as he left the Costco parking lot and arrested him nearby.

Xu’s purse was quickly returned to her.

She says it’s an eye-opening reminder that crimes can happen in a matter of seconds – and to always lock her car.