South Dakota Gov. Dennis Daugaard signed into law Friday a measure allowing the state’s school districts to arm teachers and other personnel with guns, the first of its kind since the Connecticut school shooting, the Associated Press reports. Supporters say the so-called sentinels could help prevent tragedies such as December’s shooting at Sandy Hook Elementary in Newtown, Conn., in which 20 students and six teachers died. The law will go into effect July 1. The bill’s main sponsor, Rep. Scott Craig, R-Rapid City, said he started working with federal law enforcement officials on the measure in early November, and the Connecticut tragedy weeks later “only affirmed the rightness of this bill.” He said the measure does not force a district to arm its teachers or force teachers to carry a gun…