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

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 "a mass casualty attack" at a Houston-area high school, the FBI said Wednesday night. The teen girls were accused of threatening to place pipe bombs and shoot their peers,