The World Health Organisation expressed grave concern on Tuesday for hospitals still partly operating in war-stricken northern Gaza, where one hospital director described the situation as an ‘extreme catastrophe’.’We are very, very concerned, and it's getting harder and harder to get the aid in. It's getting harder and harder to get the specialist personnel in at a time when there is greater and greater need,’ WHO spokeswoman Margaret Harris told journalists in Geneva.She said the organisation was ‘particularly concerned about Kamal Adwan Hospital’ in Beit Lahia, where Israeli forces launched an offensive against Hamas and other Palestinian groups last month.Kamal Adwan Hospital director Hossam Abu Safiyeh told AFP by phone: ‘The situation in northern Gaza is that of an extreme catastrophe.’We're beginning to lose patients because we lack medical supplies and personnel,’ he said.Abu Safiyeh added that his hospital had been ‘targeted many times by the occupation forces, most recently’ on Monday.’A large number of children and elderly people continue to arrive suffering from malnutrition,’ the doctor said.He accused Israel of ‘blocking the entry of food, water, medical staff and materials destined for the north’ of the Gaza Strip.The WHO's Harris estimated that between November 8 and 16, ‘four WHO missions we were trying to get up to go were denied’.’There's a lack of food and drinking water, shortage of medical supplies. There's really only enough for two weeks at the very best,’ she said.In its latest update on the situation in northern Gaza, the UN humanitarian office OCHA said Tuesday that ‘access to the Kamal Adwan, Al Awda and Indonesian hospitals remains severely restricted amid severe shortages of medical supplies, fuel and blood units’.Meanwhile, Gaza's civil defence agency said on Wednesday that at least 17 people, including a baby, were killed in Israeli air strikes.The Israeli military said one of its soldiers was killed and another seriously wounded during combat in the north of the Gaza Strip.The baby was killed in nighttime shelling of the Nuseirat refugee camp, civil defence spokesman Mahmud Bassal said, adding a shell killed two other people west of the camp in central Gaza.A drone strike killed two people, including a 15-year-old girl, at a school-turned-shelter for displaced people in the northern city of Beit Lahia, he said.The military campaign has forced at least 100,000 people to flee for Gaza City and nearby areas, said Louise Wateridge, spokeswoman for the UN Palestinian refugee agency UNRWA.In Jabalia, also in Gaza's far north, emergency workers on Wednesday recovered the bodies of seven people from under the rubble of a house hit by an air strike the night before, Bassal said.In southern Gaza, a person was killed when a group of Palestinians was targeted near another school in the city of Rafah on Wednesday, he said.Strikes on a residential building in Gaza City killed two people, Bassal said, while a first responder from the agency was killed while trying to evacuate wounded people in the same area.In the city's Zeitun neighbourhood, an air strike killed another person and wounded several others, Bassal added.