PORTLAND, Conn. (AP) — Four students who became ill after vaping in a high school bathroom were taken to a hospital by ambulance, officials said. 

First responders were called to Portland High School on Tuesday afternoon out of an abundance of caution, Portland Schools Superintendent Philip O'Reilly said.

After using e-cigarettes in the bathroom, the four male students returned to their respective classrooms, police Capt. Ron Milardo said. A teacher sent one of the students to the nurse's office after noticing he was drowsy and not participating in class. Soon afterward, the three other boys also reported to the nurse's office with similar symptoms, he said.

"As always, student safety is of utmost concern," O'Reilly said. "The administration will thoroughly investigate the matter and will address this incident in accordance with BOE policy."

E-cigarettes heat a liquid solution that usually contains nicotine into an inhalable vapor. The nation's top health authorities say teen vaping is an epidemic that affects some 3.6 million underage users of Juul and other such devices.

Federal law prohibits sales to those under 18, though many high schoolers report getting them from older students or online. In recent months, government officials have rolled out a series of proposals aimed at keeping the products away from youngsters, including tightening sales in convenience stores and online.