A tunnel being dug in Gaza under the aegis of the ruling Hamas group collapsed on Thursday, killing a member of the organization’s military wing, Izz ad-Din al-Qassam Brigades, Hamas said.

The dead man was named as Muhammad Musa al Astal from Khan Younis.

The tunnel caved in near the city of Khan Younis in southern Gaza, the Izz ad-Din al-Qassam Brigades confirmed. It was the latest in a spate of such collapses. Only five days ago, another tunnel caved in near the Zeitoun neighborhood in the eastern part of the Strip, injuring five members of Hamas’s military wing.

Members of Hamas accused Israel of collapsing the tunnel, The Jerusalem Post and the Maariv websites reported, saying they had seen soldiers on the Gaza border using liquid explosives and “causing small earthquakes” to bring down tunnels dug by the group.

The past two months have seen seven tunnels collapse, most of them in the Khan Younis area, and two in Zeitoun.

Around a month ago, the 23-year-old nephew of Hamas leader Mahmoud al-Zahar was killed in a tunnel accident.

Just before that, a tunnel collapsed in the area of Jabalia, in the north of the Palestinian enclave, after heavy rain and floods, killing seven excavators and injuring others.

A system of tunnels has been dug by Hamas into Israel in order to facilitate cross-border attacks. During the 2014 Israel-Hamas war, Palestinian gunmen emerged from tunnels on several occasions to ambush IDF soldiers, killing several. Israel said it destroyed more than 30 tunnels during the 50-day conflict, about one-third of which extended beneath the Gaza border into Israel. Officials say Hamas has redoubled its efforts to dig across the border into Israel in recent months.

Israel has spent over NIS one billion (some $250 million) since 2004 in attempts to thwart tunneling under the border, an Israeli TV report said last month. The money has gone toward developing technology to discover the locations of such tunnels and unspecified “operational efforts,” Channel 2 news said.

Many other tunnels are used to smuggle goods and weapons in and out of the Strip through Rafah on the Egyptian border, in the face of Israel and Egypt’s naval blockade of the enclave and their strict supervision of land borders with the Strip.

Egypt has created a buffer zone in the northern Sinai Peninsula, which it controls, destroying hundreds of tunnels leading in and out of the southern part of the Strip, sometimes by pumping sea water in. That border has remained largely closed since the overthrow of Egyptian president Mohamed Morsi of the Hamas-allied Muslim Brotherhood.