Two families in Texas are asking for the public’s help after two sixth-grade girls vanished early Tuesday and haven’t been heard from since.

According to KTRK, Mary Tran Le, 13, and Tianny Granja, 12, were last seen heading to the bus stop on the 8300 block of Wilcrest in Alief. Their phones are reportedly off and their families said they believe the Owens Intermediate School students are participating in the 48-hour challenge—an alarming trend where participants disconnect from social media and vanish for a two-day period.

“They were talking about the challenge the other day,” Dayanna Gomez, Granja’s mother, told the Daily Beast. “I just want to find my daughter, and I hope she is just hiding and not in danger.”

The family was reportedly first alerted to the 12-year-old’s disappearance when a school receptionist called them regarding her absence.

Authorities told the outlet that the challenge originated on Facebook and that participants are given “points” for every online reference about their disappearance. However, it’s unclear whether they’ve connected the pair’s disappearance to the online trend.

KTRK reported that Le was described as being 4 feet, 11 inches tall, weighing 65 pounds, and having black hair with brown tips and brown eyes. She was reportedly last seen wearing a blue shirt, blue pants, and red sneakers.

Granja was described as being 5 feet, 3 inches tall, weighing 120 pounds, and having brown curly hair with red tips and brown eyes. She was reportedly last seen wearing a white shirt, khaki pants, and sneakers.

Reports stated that the girls are believed to be traveling together.

This is an ongoing investigation. Anyone with information regarding Mary Tran Le and Tianny Granja’s whereabouts can call Houston Police Department Missing Persons at 832-394-1816.

[Featured image: Mary Tran Le, Tianny Granja/handout]