Just four days after the deadly mass shooting at Sandy Hook Elementary in Newtown, Conn., Michigan Gov. Rick Snyder rejected a bill Tuesday that would have allowed concealed weapons in schools, day care centers and select other public areas.

The veto marks a win for the American Federation of Teachers, who on Sunday wrote a letter urging the Republican governor to toss the bill. The teachers union argued that Friday's shooting is "a chilling and heartbreaking reminder" that "firearms have absolutely no place in our schools."

The concealed-carry bill passed the state legislature late Thursday, and would have extended the rights of gun owners with extra training to carry concealed guns in schools. The AFT, the country's second largest teachers union, wrote in response:

Permitting firearms in schools—visible or concealed—enables a dangerous set of circumstances that can result in similar tragic outcomes. 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.

Snyder has called for a comprehensive analysis of the state's services for at-risk children, saying Michigan needs a "more comprehensive review of issues relating to gun violence."

Still, the AFT may be facing further challenges. Snyder's veto of guns in schools comes as a number of leading politicians in other states call for just the opposite. Republican Virginia Gov. Bob McDonnell said Tuesday, just before Snyder's decision, that guns in schools is a "timely" and "reasonable" discussion in light of the tragedy in Newtown.

As of Tuesday, lawmakers in at least six states, from Tennessee to Oklahoma, are outlining plans to allow teachers to carry guns in school, or even to require some teachers to be armed.

One school in Texas does permit concealed carry by teachers, and former Education Secretary Bill Bennett took to "Meet the Press" on Sunday to express his support for arming school staff.

But AFT President Randi Weingarten said on the program that more guns aren't the answer. "Schools have to be safe sanctuaries," she said. "We need to actually stop this routine view that just having more guns will actually make people safer. We are opposed to having someone who has access to guns."

Earlier on HuffPost: