WTVD reports the call came in at about 6:30 a.m. Friday morning.
Officials have confirmed the "active shooter" was, in fact, malfunctioning equipment.
Topsail High School, Topsail Middle School, and Topsail Elementary School were all put on lockdown.
James Rowell said the crews are still searching the building as a precaution, but they have not found any evidence of an active shooter. There have been no reports of injuries.
Deputies did find an HVAC unit that was malfunctioning and making sounds similar to gunshots.
Pender County schools said via Twitter early Friday that all campuses on the eastern side of the county are on lockdown.More news: ‘Get up, he’s coming’: California bar shooting survivor recounts horror
Parents and students are gathering in the parking lot of a Lowes Foods.
"There's no active shooter", said Pender County Emergency Management Director Tom Collins, reported the StarNews in Wilmington.
Law enforcement was responding on Friday to active shooter situation at a high school in North Carolina, local media reported.
All of the schools in the district have been placed in lock down.
Two Topsail High School students were arrested in May after allegedly bringing weapons onto campus, including one student who went to school armed with a semi-automatic rifle. According to its website, school begins at 8:30 a.m. All other schools have returned to normal operations.