A Nebraska lawmaker has introduced a bill to allow school administrators, teachers and security staff to carry concealed handguns in schools.

Sen. Mark Christensen of Imperial introduced the bill two weeks after a 17-year-old killed his vice principal and shot his principal before killing himself.

Christensen says he has always opposed a ban on handguns in schools, but he had no plans to introduce his bill until the shootings on Jan. 5.

He says many schools don't even let security officers carry guns, leaving students and school employees "helpless in the face of a shooter."

The National Conference of State Legislatures says 42 states and the District of Columbia have banned guns in schools, but it could not say whether any states allow them.