Two teenage girls arrested Wednesday evening are accused of posting online threats of an attack on a Spring Branch ISD school, according to the Montgomery County Sheriff's Office. The identities of the girls were not released.

Two high school students in the Houston area are in police custody and accused of plotting a “mass casualty attack” at a Spring Branch ISD campus, according to the FBI’s Houston office.

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