"The smell of blood is everywhere," says Dr. Mohammad Mattar, the head of the radiology department at Al Shifa Hospital, the Gaza Strip's largest medical complex. There aren't enough beds to hold all the patients. "Others are on the floor."

Mattar says that because it's tradition in Gaza for parents, children, brothers and sisters to live in the same building, when a bombardment happens, entire families are killed or injured. Wounded relatives then arrive at the hospital en masse. The sheer volume of medical need is overwhelming the small and exhausted number of staff, he says.

It's a common and tragic refrain among health professionals in Gaza. As the war between Hamas and Israel grinds into its seventh day with a blockade that's sealed off Gaza from the rest of the world, the medical situation for Gazans is increasingly desperate. And Israel has now issued a declaration that Gazans should evacuate the north within 24 hours, a harbinger of even more intense conflict.

Israel launched its first retaliatory strike in Gaza several hours after the unprecedented attack by Hamas militants began early Saturday morning. The Hamas attackers killed at least 1,300 people in Israel and returned to Gaza with an estimated 150 hostages. Children and the elderly were among the victims. The Palestinian Health Ministry says Israel's ensuing bombardment in the territory has killed more than 1,500 Palestinians and wounded thousands more who now require medical attention. Plus, there are those in need of routine medical care and drugs.

Israel has reported that Hamas hides weapons and soldiers within and near hospitals and health facilities, complicating its military attacks.

As of Thursday, the World Health Organization had documented at least 34 health care-related attacks (involving health workers, facilities and ambulances) and warns that the health system in Gaza is at a breaking point.

On Wednesday night, bombs exploded near Al-Quds Hospital, says Nadal Abed, an orthopedic surgeon with the Ministry of Health in Gaza.

"The wounded patient[s] have difficult injuries due to explosive[s]," he says, "multiple injur[ies] in head, in chest, in abdomen, in extremities."

Abed was reassigned to Al-Quds on Monday morning where his job is to put people back together — by removing shrapnel and resetting broken bones. He says the wait for surgery can take days. Despite his working 24-hour shifts, there are too many patients and too few surgeons. Plus, he says he's dealing with dwindling surgical supplies.

Ghassan Abu-Sittah, a plastic and reconstructive surgeon based in London who traveled to Gaza early in the week to tend the wounded, reports similar injuries among patients at Al Awda hospital. "Basically, the patients are all blast injury patients with shrapnel injuries, crush injuries from collapsed homes, burns," he says.

"Everybody that I'm seeing is being fished out of the rubble of their homes and they're caked in mud and gravel and masonry. And even the shrapnel that you take out of their bodies is masonry and glass and household building material."

Israel has switched off Gaza's electricity, so most power including for hospitals is now coming from backup generators that run on diesel. "If that runs out," says Dr. Abu-Sittah, "then the hospitals will go dark because there's no electricity." It's a scenario that WHO warns would have devastating impacts on the most vulnerable groups — not only the severely injured but patients in intensive care and newborns dependent on incubators.

"In normal time without escalation," says Dr. Abed, "we have difficulties, I mean, big difficulties. And with this situation with big numbers of wounded patients, the health sector is about to fail, actually."

One strand of that failure is already evident for those with conditions predating the war.

"I have been receiving calls from patients who have, for example, epilepsy or neuropathy or multiple sclerosis or stroke who run out of their medications and they need a prescription," says Belal Aldabbour, a clinical neurologist who, during calmer times, saw patients in a private practice and taught medicine at the Islamic University of Gaza.

But he says a lot of pharmacies are now shuttered. And those that have remained open are practically empty due to the cutoff of all supplies to Gaza, including medications. Patients who are unable to continue taking drugs for these conditions can suffer pain and seizures.

"The best solution would be to halt the conflict immediately," says Dr. Aldabbour. "But I'm aware that this is at the hands of the politicians."

WHO and King Abdullah II of Jordan have called upon the immediate establishment of a humanitarian corridor to get urgently needed food, water and medical supplies to Palestinians within Gaza who have been sealed off by an absolute blockade. (Previously, since 2007, Gaza had been under a partial blockade by both Israel and Egypt.)

Dr. Medhat Abbas, the director general of the Palestinian Ministry of Health in Gaza, says the barricade is amplifying the crisis.

"There is no way to get extra fuel from outside," he says. "There is no way to get food. So what we need right now is a humanitarian corridor to take patients outside, to bring medical crews from outside, medical assistance and to open borders for fuel and return back electricity to Gaza Strip at once."

Without outside help, many fear continued agony from the siege. And now, the Israeli military has advised over a million Palestinians to evacuate the north half of Gaza as their siege of the embattled area progresses into its next phase — a widely expected ground invasion accompanying further air strikes.

Without reliable communication channels, Dr. Mattar says confusion is rampant. "Not all people can evacuate that easily within 24 hours," he says. "Many families have sick patients, they have elderly that cannot walk, they have kids. Many obstacles that are present. I hope this news [to evacuate is] not true."

WHO says that moving vulnerable individuals like this is tantamount to "a death sentence. Asking health workers to do so is beyond cruel."

"We don't have options," says Dr. Aldabbour. "We just do what we have to do. We survive day to day."

Aldabbour thinks a lot about his own situation — "I have a career, I have dreams," he says — and more importantly, about the survival of his own family. He tells his two young boys that the war will end soon, although he says his older son doesn't always believe him.

He and his wife refuse to endure the war in separate places. "We either die together or live together," he says. "Hopefully it is the latter."