On school days, thousands of US-born children cross the US-Mexico border to attend school. That’s the case for Julia Isabel Amparo Medina, 9, and her brother, Oscar Amparo Medina, 14. But on Monday, Julia was detained for more than 30 hours by US Customs and Border Protection when she was just trying to go to school in San Ysidro.

Early in the morning, Julia and Oscar waited in a car driven by Michelle Cardenas, one of their mom’s friends. But with the heavy traffic, Michelle advised the siblings, who have US passports, and her children to take the pedestrian walkway so they could enter the US. Michelle planned to order them an Uber, so they could arrive to school in time, but their mother, Thelma Galaxia, says her children weren’t able to cross.

CBP officers reportedly thought that Julia didn’t look like the person in her passport. Instead, they accused her of being her cousin, Melanie. The passport card that she presented to officers has a photo of herself when she was younger.

CBP said it took Julia into custody because she “provided inconsistent information during her inspection” and that the agency had to “perform due diligence in confirming her identity and citizenship,” according to NBC San Diego. However, CBP didn’t have any comments when asked why it needed 32 hours to confirm Julia’s identity.

Galaxia added that her son felt guilty after he was forced to sign a paper that said his sister was his cousin. “That is not true,” she said. “She is my daughter. He was told that he would be taken to jail and they were going to charge him for human trafficking and sex trafficking.”

Julia ended up by herself, an experience that was understandably rough for her. Several times throughout the night, she woke up.

“I was scared. I was sad because I didn’t have my mom or my brother,” she told NBC San Diego. “I was completely by myself.”

Galaxia turned to the media and Mexican consulate for help. About 30 hours after her daughter was detained, she received a call from the Mexican consulate saying her daughter would be released at the San Ysidro Port of Entry.