(HELENA, Mont.) — An improvised explosive device detonated on the playground of a Montana elementary school Tuesday, authorities said.No one was injured, according to the Lewis and Clark County Sheriff’s Office, but students at the Rossiter Elementary School in Helena are being evacuated.The IED was described by authorities as a soda bottle type device covered in duct tape.No threat had been made, authorities said, and no damage to the building was reported.All Helena District 1 Schools and East Helena Schools are on lockdown and will be searched by law enforcement, the sheriff’s office said.Agents with the FBI and the ATF (Bureau of Alcohol, Tobacco, Firearms and Explosives) are at the scene.This story is developing. Check back for updates.Copyright © 2019, ABC Audio. All rights reserved.