The World Health Organization says the number of protesters wounded in border clashes with Israel was “very overwhelming” for Gaza’s health system.

Citing figures from the Health Ministry and a group of aid agencies, WHO official Mahmoud Daher told The Associated Press Tuesday that 2,771 people were wounded in Monday’s unrest. Of those, 1,360 were wounded by live fire, 400 from shrapnel and 980 from gas inhalation. He said the majority of those wounded by live fire were struck in their lower limbs.

Daher says that nearly 1,800 of the wounded sought hospital care, putting additional pressure on Gaza’s already stressed hospitals, which endure equipment and medicine shortages and face power cuts like the rest of the territory.

Daher says the numbers were comparable to wartime situations. “It is really massive in terms of numbers,” he said

Turkey has lowered flags to half-mast to mark three days of mourning for the Palestinians killed and wounded in the Gaza border protest.

The gesture comes as the government invites members of the Organization of Islamic Cooperation for an extraordinary session Friday.

Speaking late Monday, the Turkish government’s spokesman announced the official mourning period after Israeli forces killed 58 Palestinians, most by gunfire, as they protested the Gaza blockade and the relocation of the U.S. embassy to Jerusalem.

Bekir Bozdag slammed Israel for the “massacre” and said “the U.S. now has Palestinian blood on its hands.” He said the day would be remembered as “bloody Monday.”