A tunnel constructed by the Islamist group Hamas in the Gaza Strip collapsed Wednesday evening, hours after members of the terrorist organization buried two fighters killed in another shaft collapse a day before.

The tunnel was located in the Zeitoun neighborhood of Gaza City, according to Palestinian reports. It was not immediately clear whether there were any casualties.

There were also reports of a second tunnel collapse near Rafah, in the southern Gaza Strip.

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Hamas forces were said to block off areas around both collapses.

The collapses would be the third and fourth in recent days, amid reports that the terror group has ramped up activity in digging underground passages beneath the Gaza Strip, some of which are believed to extend into Israeli territory.

IDF Maj. Gen. Yoav Mordechai, head of the Coordinator of Government Activities in the Territories, refused to say whether Israel was involved in the tunnel collapses when asked by the Palestinian Ma’an news agency.

“God knows,” he answered, according to the news agency. “I would suggest the residents of the Gaza Strip not to occupy themselves with the tunnels and to get away from them, especially after seeing the results in recent days,” he added.

IDF officials and southern residents have expressed concern in recent days that Hamas is rebuilding a series of subterranean passages, used for attacking Israel, which were destroyed during the 2014 war between Israel and Gaza fighters.

On Sunday, Prime Minister Benjamin Netanyahu responded to critics charging his government was failing to deal with newly dug tunnels under the Israel-Hamas frontier, threatening to blow up the underground passages if need be.

“We are working methodically and calmly against all threats, including threats from Hamas, both with defensive and offensive measures. And of course, in the event we are attacked from tunnels in the Gaza Strip, we will act very forcefully against Hamas, and with much more force than Operation Protective Edge,” Netanyahu told a conference of Israeli diplomats, referring to the 50-day war in the Gaza Strip in 2014.

During that war, Israeli troops uncovered and destroyed dozens of tunnels, but only after Netanyahu approved a ground invasion of the Strip amid heavy pressure from coalition allies to expand what had — to that point — been an air campaign.

Hamas built dozens of tunnels into Israel, many of which were used to carry out attacks against soldiers during the 2014 war.

Last week, a senior defense official said Hamas’s military wing had rehabilitated itself and was ready for a fresh round of hostilities with Israel. Other military leaders have said intensive tunnel rebuilding is underway.

Over the weekend, residents of areas near the Gaza Strip complained that tunnel digging into Israel from the Hamas-run territory has come so close to their homes that it has caused their floors to shake.

The Islamist movement that runs the Gaza Strip said the two men killed in Tuesday night’s tunnel collapse belonged to its armed wing, the Izz ad-Din al-Qassam Brigades. Hundreds of men, many armed and wearing balaclavas, took part in the funeral.

Hamas official Mahmoud al-Zahar said Wednesday that the Islamist group’s attack tunnels in the Gaza Strip had already reached into Israeli territory.

“The tunnels reach deep into the territory occupied in 1948,” said the Hamas official during the funeral for one of the fighters. “The [tunnels] reach [further] than Gaza.”

Later, however, al-Zahar toned down the rhetoric, and seemed to deny his earlier statements.

“The resistance tunnels are defensive tunnels for the protection of our people in the face of any Israeli aggression,” he added.

Ismail Haniyah, Hamas’s leader in Gaza, called the two men “martyrs” and praised “those who work silently underground for us to live in dignity on earth.”

Another tunnel collapse caused by bad weather on January 26 killed seven Al-Qassam fighters.