Recently, a Palestinian farmer and his grandson were killed by a tank-fired shell while walking on their land near the border with Israel at the north end of the Gaza trip. Let's take a look at the background situation.
Here is a map of the Gaza Strip showing the perimeter zones: "no-go" in red, where anyone entering will be shot and "high-risk" in orange, where anyone entering might be shot. See the second map for a close-up of where the incident of the farmer/grandson occurred.
The grandfather/grandson were in the "high risk" area (blue arrow) between the Erez crossing to Israel and the Palestinian town of Beit Hanoun (bet ha-NOON)
Though the two were killed by tank fire, remote-controlled machine gun towers are the typical means of enforcing exclusion. Here is a picture of one of the machine gun towers. The guns are fired by women in the IDF using joy-sticks located in a control room. This means that any attacks on the towers will not endanger the operators. The tower shown is near Khan Yunis, not Erez, but the operation is the same.
Though the no-go zone extends on 300 meters from the border, the high-risk zone extends without clear definition but about 1300 meters from the border, or 3/4 of a mile, all of it Palestinian land. The United Nations report, from which I am drawing my pictures, says this is 17% of the entire land area of the Gaza Strip, so it isn't surprising that farm land is part of it - hence the presence of the farmer/grandson on their land. The Israeli army makes it a practice to clear this land of crops so that it can maintain a clear line of sight. Palestinian farmers have taken to growing very low-height crops in hope of continuing to farm.
Now let's get a feel for the area. Here is a video of demonstrators appearing at the same site as the killings to protest them. You will hear the machine gun tower begin firing in warning and you will see the actual terrain and the tower for yourself.