CLARKSTOWN, N.Y. (UPDATE) -- A plastic bottle filled with concrete that at first appeared suspicious forced the evacuation of Clarkstown South High School on Wednesday, authorities said.
A staffer found what was first feared to be an explosive device before 11 a.m., police said.
The Rockland County Sheriff's Department Bomb Squad collected it and available K-9 units from Clarkstown, New York State Police, U.S. Park Police, MTA police and the sheriff's department did a cautionary sweep.
Classes were to resume as normal on Thursday, authorities said.
Meanwhile, police were investigating.