GAZA/JERUSALEM -- Israeli authorities have begun freeing Palestinian prisoners from jails as part of an exchange deal after Hamas released 20 Israeli hostages, Palestinian sources said on Monday.

According to the deal agreed by Israel and Hamas, about 2,000 Palestinian detainees and prisoners are to be freed.

Earlier in the day, Israel confirmed that 13 hostages, the last living Israelis held by Hamas in Gaza, had been handed over to the Red Cross.

The 13 men are currently being accompanied by soldiers and Shin Bet agents on their way back to Israel, where they will undergo an initial medical assessment and reunite with their families, said the Israeli military in a statement.

Hamas confirmed in a statement that it has released all 20 living Israeli hostages, as a step to implement a truce pact with Israel.

The group reaffirmed commitment to fulfilling its obligations, stressing the importance of the mediators' work to compel Israel to fulfill its obligations under the deal and complete the implementation of all its provisions.

A Hamas official told the Saudi Asharq News TV that several deceased hostages will be rendered later on Monday. There are a total of 28 deceased hostages that Hamas is required to return to Israel under the ceasefire agreement.

Israel released the first photos of the hostages arriving in the country and meeting Israeli officers, showing all of them standing and without any visible injuries.