Tobacco use among American middle and high school students -- especially electronic cigarette use -- declined sharply in 2016 from the year before following several years of strong growth, according to a study out Thursday.

The number of students who said they had used a tobacco product in the past 30 days was 3.9 million in 2016, down from 4.7 million in 2015, a 17 percent drop, the Centers for Disease Control and Prevention (CDC) and the US Food and Drug Administration (FDA) data showed. 

The tobacco users made up 20.2 percent of high school students and 7.2 percent of middle school students.

The decline mostly reflected a 26.7 percent drop in the use of electronic cigarettes, the most popular tobacco product among the students surveyed.

There were 2.2 million young e-cigarette users in 2016, down from 3 million in 2015. They comprised 11.3 percent of high school and 4.3 percent of middle school students.

Read also: Indonesia may ban cigarette advertisements from TV, radio

E-cigarettes and hookah usage had grown sharply from 2011 to 2014. The other forms of tobacco used by students include cigarettes, cigars, smokeless tobacco, pipe tobacco and bidis.

"Far too many young people are still using tobacco products, so we must continue to prioritize proven strategies to protect our youth from this preventable health risk," CDC Acting Director Anne Schuchat said in a statement.

Tobacco prevention and control strategies from all levels of government likely contributed to the reduction in usage, the authors of the report said, but stressed that continued surveillance was needed to determine if the trend continues.

"While these latest numbers are encouraging, it is critical that we work to ensure this downward trend continues over the long term across all tobacco products," FDA Commissioner Scott Gottlieb said.