makes you stop and feel sick to your stomach when you imagine the kids quietly taking an exam, sitting there in that room. i know this happened in pakis n pakistan. the group has a long history of targeting the united states that was responsible. >> reporter: evening, erin. horror of what happened in pakistan. this is a group well-known, the ttb or pakistani taliban have a long history of brutal violence and behind attacks here in the united states. back in 2010 they were said to be behind the failed attempt to set a bomb in new york's time square. in 2009 they attacked a cia base in afghanistan killing seven cia agents there. they have repeatedly vowed to attack the united states. whether they are capable of actually lunching an attack overseas outside of pakistan would remain to be seen but today's event inside of pakistan, absolutely horrific.