JEFFERSON CITY, Mo. -

Missouri Gov. Jay Nixon has vetoed legislation allowing specially trained teachers to carry concealed guns in public schools.

The Democratic governor said Monday that the legislation would have jeopardized student safety. But supporters said it would have helped protect students from armed intruders.

Missouri's Republican-led Legislature began considering the legislation after the deadly 2012 mass shooting at Sandy Hook Elementary School in Newtown, Connecticut.

The legislation would have allowed public school districts to designate certain teachers or administrators as "school protection officers," who would undergo special training to carry concealed weapons.

State lawmakers would need a two-thirds majority in each chamber to override Nixon's veto.  The bill met that mark when it originally passed the House. It fell two votes short in the Senate, but three Republican senators were absent.

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