Technicians discovered 145 coffins beneath a high school near Tampa, Florida, and officials said more collections of graves could be found.

The Hillsborough County school district revealed Wednesday that geophysical technicians had discovered evidence of the graves beneath Clarence Leon King High School a month after a school board member informed the district about the possible location of Ridgewood Cemetery, a burial ground for African American paupers from the 1940s.

Technicians spent two weeks combed the school ground and the surrounding area with ground-penetrating radar and discovered the graves an acre of land used by the school’s agriculture building.

“The first area that was scanned is on the southern edge of the King High School campus,” Hillsborough school district said in a statement. “This is the area where the technicians found clear evidence of burials. Ground-penetrating radar found approximately 145 coffins, buried 3- to 5-feet deep.”

The school said records indicate the site could contain as many as 260 graves. The school district said to expect discrepancies in the numbers due to the condition of the graves and the fact that many of the remains are children or infants.

The discovery has also led to investigations by other facilities, including MacDill Air Force Base.

“As of now we cannot confirm the existence of a cemetery on base,” spokesman Lt. Brandon Hanner told the Tampa Bay Times. “However, we do have resources that will be allocated in the near future to either confirm or deny it is on the base.”

High School
In this representational image, pupils wait for the start of the first written test in philosophy at a school in Paris on June 15, 2017. Martin Bureau/AFP/Getty Images