Michigan state senators voted Thursday to allow citizens with concealed carry permits to carry their weapons on school property, but the American Federation of Teachers argues that the Friday shooting in Connecticut proves people shouldn’t be armed at school.

“Firearms have absolutely no place in our schools—the Dec. 14, 2012, tragic massacre at Sandy Hook Elementary School in Newtown, Conn., is a chilling and heartbreaking reminder of this,”wrote Randi Weingarten, president of AFT, and AFT Michigan president David Hecker in a letter to Gov. Rick Snyder, R-Mich.

“Permitting firearms in schools—visible or concealed—enables a dangerous set of circumstances that can result in similar tragic outcomes,” Weingarten and Hecker added in calling for Snyder to veto the legislation. “We should be doing everything we can to reduce the possibility of any gunfire in schools, and concentrate on ways to keep all guns off school property and ensure the safety of children and school employees.”

Twenty-six people, including 20 children, were murdered in an elementary school after a man forced his way into the building and opened fire in multiple classrooms.

“This kind of tragedy is hard to process, but if one person – a faculty member or a parent – could legally carry, at least it could have limited some of the mayhem,”  Rob Harris, media director for Michigan Open Carry Inc., told USA Today on Friday after the Sandy Hook shooting took place.