Muslim worshippers clashed with Israeli police at the Temple Mount on Wednesday just hours before Israel was set to hold a Jerusalem Day celebration to mark the date the Jewish state captured East Jerusalem in 1967.

Four Muslim worshippers suffered slight head injuries from rubber bullets and tear gas fired by Israeli police, Palestinian news agency Ma’an reported. They were treated and released from a local hospital.

An Israeli police officer was wounded when a masked Arab protester threw a rock, Israeli daily newspaper Haaretz reported.

The clash unfolded after “a small group of rioters” created a disturbance on the Temple Mount, Israeli police spokesman Micky Rosenfeld told Associated Press. Azzam Khatib, director of the Islamic religious authority that oversees the compound, said Israeli police “stormed” the area and stopped worshippers from entering the compound, known to Muslims as the Noble Sanctuary.

The violence occurred just hours before Israel was set to hold a Jerusalem Day flag procession, an event that draws thousands of Israelis who march from the western part of the city to the Western Wall, the holiest site where Jews can pray.

Hundreds of police were deployed before the march, Rosenfeld said. The event has spurred clashes before and Israeli participants have spewed racial epithets at Arabs in Jerusalem’s Old City, according to Haaretz.