An Israeli army raid killed 11 Palestinians including a teenager Wednesday in Nablus, the Palestinian health ministry said, in the deadliest escalation in the occupied West Bank since 2005.

More than 80 Palestinians suffered gunshot wounds, the Palestinian ministry said, in what the Israeli army called a “counter-terrorism” operation, spurring international concern and calls for calm.

Top Palestinian official Hussein al-Sheik decried the incursion as a “massacre” and called for “international protection for our people”.

The Israeli army said the raid targeted militant suspects “in a hideout apartment” accused of shootings in the West Bank. It added troops came under fire but suffered no casualties.

United Nations Secretary-General Antonio Guterres said “the situation in the occupied Palestinian territory is at its most combustible in years”, with tensions “sky high” as “the peace process remains stalled”.

“Our immediate priority must be to prevent further escalation, reduce tensions and restore calm,” Guterres told the UN Committee on the Exercise of the Inalienable Rights of the Palestinian People.

The death toll surpassed that of an Israeli army raid last month in Jenin, further north, which had been the deadliest West Bank operation since the second intifada, or Palestinian uprising, of 2000 to 2005.

The Israeli military said one of the wanted suspects who had fled the building was “neutralized”, along with two others who had opened fire at the property.

The suspects and Israeli forces “exchanged fire… there were also rockets that were fired on the house” by the army, spokesman Richard Hecht told journalists.

Rocks, explosive devices and Molotov cocktails were hurled at the troops, the army said.

The Palestinian health ministry said those killed “as a result of the occupation’s aggression on Nablus” were aged between 16 and 72.

Hours after the raid, the ministry announced the death of a 66-year-old man from tear gas inhalation.