The IDF determined Monday that three openings in the ground, discovered close to homes inside communities in the Gaza border area on Sunday, were not tunnels crossing over from the Strip, as was previously suspected.

Military engineers who investigated the openings said they were probably natural sinkholes, not man-made underground constructions. The openings were later filled with sand.

The Israel Defense Forces and security forces had on Sunday closed off the areas around the openings as a precaution against possible terror infiltration.

The forces have since been removed from the area, according to Channel 2.

The IDF said in a statement that, continuing the efforts begun during Operation Protective Edge, the military was working to defend the Gaza border area communities and that security forces were familiar with the openings.

“These are known shafts, and if more shafts are found they will be dealt with from within our territory,” the IDF said Sunday.

One of the stated aims of Operation Protective Edge was to locate and destroy the network of attack tunnels dug under the border by Hamas and used by terrorists to enter Israel.

Eleven IDF soldiers were killed in several ambushes launched by terrorists who had emerged from the tunnels. During the ground offensive into Gaza, the IDF blew up over 30 tunnels.

Adiv Sterman contributed to this report.