WASHINGTON - Armed security officers are becoming more prevalent at US schools, according to a federal study released on Thursday amid a heated debate over whether teachers and other school officials should carry guns.

Armed officers were present at least once a week in 43 percent of all public schools during the 2015-16 school year, compared with 31 percent of schools a decade before, according to data from a survey conducted by the National Center for Education Statistics.

Last month's mass shooting at a Florida high school put renewed focus on the role of armed school security guards, after a video showed that a sheriff's deputy at the school approached but did not enter the building where the attack was taking place.

The study came out a day after Education Secretary Betsy DeVos kicked off a federal school safety panel. DeVos has said that schools should have the option to arm teachers. She's being criticized by teachers' unions for not including educators, students and experts in the panel, which consists only of her and three other Cabinet secretaries.

The percentage of schools with a security guard, a school resource officer or other sworn law enforcement officer on campus at least once a week has gone up from 42 percent in 2005-06 to 57 percent a decade later. While security at schools of all grade levels increased, the shift is clearer among elementary schools, where the share with security staff has gone from 26 percent to 45 percent in the same time period.