Hannah Bridges was home alone when the strange man came around.

“I just heard this guy keep knocking and knocking,” she tells CBS 2’s Roseanne Tellez.

The Mount Prospect teen called her mom, who was driving home from work.

“I said, ‘I’ll turn my camera on and I’ll watch him,’” her mother, Bonnie Bridges, says.

She activated her camera in the living room and called up the picture on a cell phone app. She saw the intruder kick in the front door.

“My entire body went numb. I just immediately called 9-1-1,” Bonnie Bridges says.

Hannah Bridges screamed, sending the intruder on his way. The video led to his arrest.

Bonnie Bridges is an advocate for people buying some kind of home security system.

“I’d say it’s definitely a must for every home in America,” she says.

She has added more security cameras inside and out and learned to use features like the siren on her camera. It can be activated from her phone.

Bonnie Bridges, the Mount Prospect mother, says her intent was really to watch her kids.

“My children were not very pleased. But after this incident, she said, ‘Mommy, I’m so glad you got that camera,’” she says.