Gaza, Oct 17 : The UN has said that the number of humanitarian staff killed while on duty in Gaza has increased to 31 after seven Civil Defence officials died in an Israeli airtsrike in the last 24 hours. On Monday, "seven Civil Defence members were killed during an airstrike, bringing the total number of humanitarian staff killed while on duty to 31", the Office for the Coordination of Humantitarian Affairs (OCHA) said in its latest situation update. The UN body said that the Hamas-controlled enclave has been "under full electricity blackout for the sixth consecutive day". "Hospitals are on the brink of collapse as their fuel reserves used to operate backup generators have been almost totally depleted, endangering the lives of thousands of patients," the update said On Sunday, the Israeli authorities resumed partial water supply to the eastern Khan Younis area, providing less than 4 per cent of the water consumed in the Gaza Strip before the latest conflict erupted on October 7. Meanwhile, the Unicef-led WASH Cluster stated that the population 'is at imminent risk of death or infectious disease outbreak if water and fuel are are not immediately allowed to enter the Strip". The OCHA also warned that the overall number of internally displaced people (IDPs) since the beginning of the ongoing conflict might have reached 1 million, including nearly 333,000 IDPs staying in UN Relief Works Agency designated emergency shelters in central and southern Gaza alone. Meanwhile, the death toll in Gaza as of Tuesday morning stood at 2,778, with 9,938 injured persons. The Palestinian Ministry of Health said that 47 entire families have been killed, amounting to about 500 people. According to official Israeli sources, at least 1,300 Israelis and foreign nationals have been killed in the Jewish nation, while 4,121 others were injured, the vast majority on October 7 when Hamas launched its massive surprise assault. The fatality toll is over three-fold the cumulative number of Israelis killed since OCHA began recording casualties in 2005 (nearly 400). /IANS