Trustees of a wealthy Dallas-area school district have backed a proposal to hire armed private security guards to patrol all 71 campuses.

The Plano Independent School District board Tuesday night endorsed a plan that could cost $2.7 million. The action was taken a month after the Connecticut school shootings that left 20 students and six educators dead.

Superintendent Richard Matkin last week sent a letter to parents indicating he planned "aggressive recommendations" for safety of the district's 55,000 students. Plano ISD also has more than 6,400 employees.

The district currently has armed liaison police officers who work for the city and are posted at high schools.

Hiring private guards would nearly triple the district's current security budget. Matkin says the funds would come from the district's savings.