What started as a quick trip to a bookstore in a New Jersey town for a teenager and her mother quickly turned into a horrifying bathroom experience — and an arrest.

Madison Delaney told NBC New York she went to use the bathroom at the Barnes & Noble in Clifton around 12:15 p.m. on Wednesday when she made the disturbing discovery: Someone was filming her inside the stall.

"I was like, that’s a camera, filming me – this isn’t supposed to be happening," Delaney said. "I was shaking really bad; I was terrified. But the only thing I could think to do was to get an employee in here, because they can get to the police."

The 18-year-old from Secaucus also knew the only way to get a store employee into the bathroom was to get in contact with her mother, so she sent a flurry of text messages. In one of them, she said "Someone next to me in the stall just used a GoPro to film ... Mom please answer ... I'm terrified."

Delaney's mother Heather quickly rushed to the bathroom with an employee, where they were able to help her daughter.

"I looked under the door and saw which one she was in. I told her it was OK to come out ... I put her behind me towards the exit of bathroom," Heather Delaney said.

They said the suspect in the stall next to Delaney's had marked it out of service, a fake likely used to prevent people from trying to open the door. After repeatedly knocking, the male suspect finally opened the door and asked, "Did I do something wrong?"

Police showed up minutes later, and placed the suspect under arrest. In a statement, Barnes & Noble said they were "disturbed to learn of the incident that happened yesterday in our store. When store employees were alerted to the situation, they immediately notified the police, and the suspect was apprehended."

Police on Friday said that 44-year-old Juan Mejia was arrested for the lewd act. The Paterson resident is accused of filming two women as they used the bathroom, and has been charged with two counts of invasion of privacy. In addition to those charges, Mejia was found to be in possession of images believed to be child pornography. He was subsequently charged with multiple counts of child endangerment and manufacturing and possessing suspected child porn.

Despite the quick resolution to the creepy situation, the victim and her mother said the ordeal still haunts them.

"I’m shocked at how I can’t remove it from my head at all, every time I think I’m distracted I see his face," Madison Delaney said.

"I didn’t really sleep last night. As a mom too I play 'What if?' What if he saw her and decided to do something else?" Heather Delaney said.

Now the mother and daughter want to raise awareness, and by sharing their story hope that others take note and are aware of their surroundings.

Mejia is being held at Passaic County Jail, and is scheduled to appear in court on February 26.