On May 15, Palestinians mark the anniversary of the ‘Nakba’ or ‘catastrophe’ which befell them following the 1948 Arab-Israeli War, when the establishment of Israel led to the expulsion of hundreds of thousands of Palestinians from their homes.

At this time of the year, tension rises between Palestinian youth and Israeli police. Photographer Uriel Sinai shot these photographs in East Jerusalem when clashes erupted after Friday prayers on May 13.

Sinai watched as Israeli police and demonstrators took positions on opposite sides of the street. After several hours of stone throwing and tear gas, a car caught on fire. While a woman in the apartment above tried to extinguish the blaze, demonstrators continued to throw stones from the cover of a wooden board. The clashes finally ended when undercover police moved in and arrested the demonstrators.

There were numerous small demonstrations around Jerusalem and throughout the West Bank Friday, with many more expected to take place this weekend.

“This time of year is very fragile,” Sinai said on Friday, “but around here, it is always like this — things could escalate very easily. Hopefully this will not be the case this time.”

On Sunday May 15, clashes between pro-Palestinian protesters and Israeli forces erupted once more. By late afternoon—after Israeli forces fired on groups of demonstrators—at least 12 protesters had been killed and dozens more injured in separate incidents along Israel’s borders.