Israel’s prison service said 39 Palestinian detainees were released on Sunday under the terms of a truce agreement between Israel and Hamas in the Gaza Strip.

The announcement came after 13 Israeli hostages were freed in the Palestinian territory under the deal, along with three Thais and a Russian-Israeli dual citizen.

The four-day truce is the first halt in fighting in the seven weeks since Hamas killed 1,200 people and took about 240 hostages back into Gaza.

Israel bombarded the enclave, mounting a ground offensive in the north. Some 14,800 Palestinians have been brutally killed, and hundreds of thousands displaced.