NBC Nightly News A cell phone video popped up on ubtube this weekend that reminds us how devastating the drug war in mexico has become and how small the victims can be. a class room full of kindergarten kids is singing a cute little song from barney the dinosaur all while a gun battle rages right outside their window. The teacher's name is marta rivera, and this morning, mexican officials praised her courage under fire. on friday, organized crime gangs fought a battle that killed five men outside the school where she teaches. inside, she calmly ordered the children to lie flat. nothing is happening, sweethearts, just put your little faces on the floor. the teacher said she shot the video because she's on the school safety committee and felt the need to record this. as they cowher from the rainfall of bullets outside, she has the children sing a barney the dinosaur song about how it's raining chocolate. if the rain drops were made of chocolate, I would love to be here. The actions of the teacher in the situation were extraordinary. the primary objective is to keep the children safe and calm. An american teacher living in monterrey who wants to remain anonymous spoke to nbc news, "it's happening everywhere. there's no way to escape the reality of what is happening here." children in mexico execute shootout drills like the duck and roll children went through in the cold war. That teacher and the children in her class know that terror all too well. george lewis, nbc news, los ...