Police say the teacher inside Cranbury School reported what they believed may have been gunshots from outside the school in Cranbury Acres Park around 11:25 a.m.
The school was placed in lockdown as a precaution as officers responded.
Two officers were in the immediate vicinity, but they did not locate anything suspicious.
Officials said other officers checked the area, canvassed individuals walking in the area as well as at Cranbury Park and no other reports of shots were received.
Officers continued to check the surrounding areas, including the trails in Cranbury Park, but nothing was found.
The lockdown was lifted just before 12:30 p.m.