According to The Times of Israel, a tunnel collapsed in southern Gaza on March 3 and killed Muhammad Musa al Astal of Khan Younis, the Hamas operative who was digging the tunnel. Just days earlier, another tunnel had collapsed, this time in eastern Gaza, injuring five Hamas operatives.

The Jerusalem Post, citing unnamed Palestinian sources, said that some Hamas operatives are blaming Israel for the tunnel collapses and are afraid to enter the tunnels. The operatives claim that they have seen Israeli soldiers on the border using liquid explosives and “causing small earthquakes” in order to destroy the tunnels.

According to The Times of Israel, seven tunnels have collapsed in the last two months, including one that killed the nephew of Hamas leader Mahmoud al-Zahar.

Back in January, at a funeral for seven Hamas operatives that were killed in a tunnel collapse, Hamas leader Ismail Haniyeh announced that Palestinian “heroes” are digging tunnels to be used in future attacks against Israel.

At that time, The Times of Israel reported that Hamas had more than 1,000 people working nonstop, six days a week, digging tunnels lined with concrete and “being dug 30 meters deep, with sophisticated engineering equipment and more advanced technological support, including engineers’ blueprints.”

Hamas’s large network of tunnels, many of which lead into Israel, was a major source of conflict during Operation Protective Edge, which was Israel’s war in the Gaza Strip in 2014. During the war, Israel destroyed more than 30 tunnels, which were used to smuggle weapons, in addition to staging terrorist attacks and kidnappings inside Israel. During Operation Protective Edge, thousands of people, the majority of whom were Palestinians, were killed and much of Gaza’s infrastructure was severely damaged.