Israeli jets attacked targets in the Gaza Strip late Saturday night, hours after a rocket was fired across the border.

Palestinian medical and security sources said five sites were hit, including training camps for the Islamic Jihad and Ezzedine al-Qassam Brigades, the military wing of Gaza’s ruling Hamas organization.

No injuries were reported.

The Israeli army said it retaliated after a rocket fired from Gaza hit an open area near Ashkelon in southern Israel without causing damage or injuries.

The two sides also exchanged rockets and strikes on Thursday, shortly after West Jerusalem called off the planned release of 26 Palestinian prisoners.

The prisoners were the last group of 104 detainees who were supposed to be freed under a confidence-building measure in US-brokered Israeli-Palestinian talks.

The Palestinian Authority subsequently signed a commitment to join 15 United Nations agencies and international treaties, defying Israeli warnings that this would halt negotiations.