HILLSBOROUGH, NJ - Township police called in multiple K9 units to check the hallways and classrooms at Hillsborough High School this morning after school officials reported two trespassers had entered the school.

The school was locked down at 10 a.m. The K9s and their handlers swept the parking lots, hallways and classrooms for more than an hour. Bus companies were contacted and students were dismissed at noon.

Township police are continuing their investigation.

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Although afternoon events at the school were cancelled, an evening tennis match and 7 p.m. Battle of the Bands were to be held, as well as any Saturday events, according to Principal Karen A. Bingert.

The principal released a letter detailing the incident:

"Earlier this morning, two trespassers entered Hillsborough High School with the morning influx of students. Shortly after that they left without obvious incident."

The letter said a staff member and student both reported seeing the two trespassers. No description was provided.

Police were called by school officials.

"Working collaboratively with the police, who mustered the additional resources of the New Jersey Detect and Render Safe (which includes the regional K9 task force), we secured dogs to check the parking lots and building to make sure that nothing dangerous had been left behind," Bingert wrote.

"In order to do this, we needed to restrict movement inside and outside the building, which resulted in the decision for an early dismissal today."