Israeli security forces detained U.S. congressional candidate Brad Lander and dozens of American and Israeli rabbis and activists near the West Bank settlement of Beitar Illit on Wednesday. They were helping Palestinians harvest olives in a grove close to the settlement.

Soldiers and police declared the grove a closed military zone and escorted the group away before detaining them. The Israeli military said farmers in the area must arrange harvesting with authorities in advance to maintain security and public order. It said the Palestinians had not submitted a request.

Lander, a Democratic House nominee and former New York City comptroller, was released after being warned, though others remained in custody initially. By Wednesday night, the New Israel Fund, a sponsor of the volunteer initiative, said approximately 90 volunteers had been released. The military said Lander was freed once his detention was brought to its attention.