One of the girls accused of plotting a pipe bomb attack and shooting at Memorial High School was ordered to be held at a Harris County facility for juvenile defendants after the 16-year-old girl's mother testified Friday about her daughter's struggles with mental health.

Evidence suggests their intent was to carry out acts of violence at a school in the Spring Branch Independent School District, law enforcement said.

Two teenagers are under arrest for allegedly plotting what the FBI is calling "a mass casualty attack" at a Houston-area high school.