Hundreds of people are reported to have been killed in a massive explosion at a crowded hospital in Gaza City, in the biggest single loss of life in the blockaded territory in all the five wars between Hamas and Israel since the militants took over the strip in 2007. The Gaza health ministry, which is run by Hamas, said at least 500 people were killed on Tuesday night in what it said was an Israeli airstrike on al-Ahli al-Arabi, also known as the Baptist hospital. A spokesperson for the Gaza civil defence put the number of killed at about 300. The bloodshed at the hospital comes 11 days into a new war between Israel and the Palestinian militant group that continues to escalate before an expected visit to the region by Joe Biden, complicating US efforts to stop the conflict spiralling across the Middle East. The Israeli military reportedly said an initial investigation suggested the explosion was caused by a failed Hamas rocket launch, before saying it was the result of a Palestinian Islamic Jihad rocket barrage. Islamic Jihad denied the Israeli allegation, and the scale of the blast appeared to be outside the militant groups’ capabilities. Footage broadcast from the ground by Al Jazeera showed a huge fire engulfing the multi-storey building, with bodies, streaks of blood and widespread debris scattered around. The hospital, which is owned by the Anglican church, was reportedly struck without any prior warning. It was previously hit by a rocket on Saturday in an attack that injured four medical staff. The hospital was hit at about 7.30pm local time. It was packed with people injured in Israeli strikes, as well as civilians seeking shelter, believing the hospital grounds to be safer than their homes after relentless Israeli attacks that have already killed more than 3,000 people. “We were operating in the hospital, there was a strong explosion, and the ceiling fell on the operating room. This is a massacre,”​ said Dr Ghassan Abu Sittah. “Nothing justifies this shocking attack on a hospital and its many patients and health workers, as well as the people who sought shelter there. ​Hospitals are not a target. ​ This bloodshed must stop. ​Enough is enough.” More than 300 casualties were taken in ambulances and private cars to Gaza City’s main hospital, al-Shifa, which was already overwhelmed with wounded from other strikes. Injured people lay on bloody floors, screaming in pain “We are squeezing five beds into a single tiny room. We need equipment, we need medicine, we need beds, we need anesthesia, we need everything,” the al-Shifa director, Mohammed Abu Selmia, told AP. “I think Gaza’s medical sector will collapse within hours.” Dr Ziad Shehadah told Al Jazeera: “What’s happened is terrible because those people, all of them, are civilians. They fled their homes and reached a place that they believed was safe – a hospital, which according to international law, is a safe place. “People left their homes thinking they were more dangerous and they move to our schools and hospitals to be safe. And in one minute, all of them have been killed at a hospital.” Aid agencies and governments around the world were quick to condemn the bombing as a war crime. The World Health Organization’s director general, Tedros Adhanom Ghebreyesus, demanded the immediate protection of civilians and healthcare in the Palestinian territory. “WHO strongly condemns the attack on Al Ahli Arab Hospital,” he tweeted. “Early reports indicate hundreds of deaths and injuries. We call for the immediate protection of civilians and healthcare.” Canon Richard Sewell, the dean of the Anglican-run St George’s College in Jerusalem, said: “Disaster: our hospital, Ahli Arab hospital, has taken a direct hit from an Israeli missile. Early reports say hundreds of women and children killed. “This is deliberate killing of vulnerable civilians. The bombs must stop now. There can be no possible justification for this.” Turkey’s foreign ministry condemned what it called a “barbaric attack” while Canada’s prime minister, Justin Trudeau, described it as “horrific and absolutely unacceptable”. Hamas, which sparked the latest war with an attack last week that killed more than 1,400 Israelis, called Tuesday’s hospital strike “a horrific massacre”. It said in a statement that most of the casualties were displaced families, patients, children and women. Before the al-Alhi blasts, Israeli strikes on Gaza had killed at least 2,778 people and wounded 9,700, according to the Gaza health ministry. Nearly two-thirds of those killed were children. The US president, Joe Biden, is due to arrive in Tel Aviv on Wednesday for talks with Israeli, Palestinian, Jordanian and Egyptian officials amid efforts by his administration to de-escalate the growing threat of a regional war. But the Palestinian Authority president, Mahmoud Abbas, who controls parts of the occupied West Bank, cancelled a planned meeting with Biden in protest at the hospital attack, declaring three days of mourning. In a statement, Abbas said: “What is taking place is genocide. We call on the international community to intervene immediately to stop this massacre. Silence is no longer acceptable.” Abbas, however, is deeply unpopular with the Palestinian public, many of whom see him as little more as a subcontractor for Israeli security after 16 years in office without elections. After news of the hospital attack spread, hundreds of people flooded the streets of major West Bank cities including Ramallah, the seat of the Palestinian Authority, where protesters hurled stones at Palestinian security forces who fired back with stun grenades. “The people want the fall of the president,” demonstrators chanted.