Egyptian security forces on Saturday destroyed eight smuggling tunnels under the Rafah border crossing between Egypt and Gaza.

Citing an Egyptian military source, the Palestinian Ma’an news agency reported that the tunnels were demolished in order to protect Egypt’s borders “in all strategic directions.”

The source said eight tunnels were demolished “under the borders in Rafah.”

Hamas uses smuggling tunnels into Egypt as a way to circumvent the Israeli blockade on the Gaza Strip and smuggle weapons, building supplies, fuel and consumer goods into the Palestinian territory.

Since the ouster of Islamist president Mohammed Morsi in July, however, the Egyptian military has clamped down on tunneling after it became clear that the subterranean routes also facilitated the transfer of military supplies, equipment and personnel to Islamist militias operating in the northern Sinai Peninsula.

The Egyptian army is engaged in a widespread military operation to regain control of Sinai from militant groups that have killed dozens of Egyptian policemen and soldiers.

In October, a senior Hamas official said that Egypt’s closure of smuggling tunnels between the Sinai Peninsula and the Gaza Strip is costing the organization $230 million in lost revenue.

Meanwhile Saturday, as the Egyptian government prepared to announce the results of a referendum on its new constitution, the country’s Health Ministry said the death toll from street violence Friday had risen to four.

The ministry said that 15 people were also injured in the clashes, which began after supporters of the ousted Islamist president took to the streets in Cairo and other provinces to denounce the draft charter. Police fired tear gas and arrested dozens in their crackdown on demonstrations held without permits.

Since a popularly backed military coup overthrew Morsi in July, Islamists have been staging near-daily protests against interim authorities they consider illegitimate. Demonstrations often end violently.

An initial, informal count showed more than 90 percent of voters backed the document. Official results will be announced by the high electoral committee later Saturday.