Herricks Middle School and Herricks High School on Long Island were both locked down for a time Tuesday afternoon after what the school district described as a "general threat."
The lockdown started before 2 p.m. and was lifted by 3 p.m.
"Based on a general threat earlier today, the police conducted an investigation at both schools out of an abundance of caution. The police have deemed everything to be safe and after-school activities will take place as usual," superintendent Fino Celano said in a message posted on the district's website.
Pictures from a district parent showed heavily armed police searching individual classrooms before the threat was cleared.
The middle school is in Albertson and the high school is in New Hyde Park.