What do we know about captives seized by Hamas in blitz on Israel?

Hamas and Israel have agreed to stop all fighting in Gaza for four days as part of an agreement in which Hamas will release 50 captives in exchange for Israel releasing 150 Palestinian women and children incarcerated in its jails, the Palestinian resistance group said in a statement on Wednesday.

The deal will allow hundreds of humanitarian, medical and fuel aid trucks to enter all parts of Gaza, the statement added. Israel estimates that at least 239 Israelis are being detained by Hamas.

Here is what we know about the captives and Palestinians in Israeli jails.

Who are the people in Hamas custody and Israeli jails?

There were about 5,200 Palestinians in Israeli prisons before October 7 when Hamas launched a surprise blitz on Israel. That number rose to 10,000 as Israel seized more Palestinians, many of them women and children.

The captives are from settler communities, including collective farms called kibbutzim and military bases in southern Israel, as well as people attending an outdoor music festival.

In addition to Israeli citizens, more than half the captives held foreign and dual citizenship from some 40 countries, including the US, Thailand, Britain, France, Argentina, Germany, Chile, Spain, and Portugal, Israel's government has said.

Was any captive released by Hamas?

Hamas has to date released four captives: US citizens Judith Raanan, 59, and her daughter, Natalie Raanan, 17, on October 20, citing "humanitarian reasons," and Israeli women Nurit Cooper, 79, and Yocheved Lifshitz, 85, on October 23.

Israel has previously announced that its forces freed one captive, Ori Megidish, a soldier, in their ground invasion of besieged Gaza on October 30, a claim Hamas denied, saying it aimed to distract the Israeli public opinion from the release of a video of three Israeli female captives earlier in October in which one captive asked Netanyahu to heed Hamas’ demands in exchange for their release.

The Israeli military said earlier this month that it recovered the bodies of two captives in Gaza City, including 19-year-old soldier Noa Marciano.

The armed wing of the Palestinian resistance group Islamic Jihad, which participated in the October 7 surprise blitz, announced late on Tuesday the death of another Israeli captive but did not identify the individual.

What have conditions been like for captives?

Hamas has said it has hidden the captives in "safe places and tunnels" in Gaza.

Lifshitz, an 85-year-old grandmother who was freed by Hamas, said that after she was seized, she was taken into underground tunnels that she compared to a spider web.

Lifshitz said her captors separated captives into small groups. She said she and a few others with her slept on mattresses on the floor of the tunnels.

Doctors provided care, and Hamas ensured conditions were hygienic, she said.

In a video released by Hamas in October, a 21-year-old French captive was shown having her injured arm treated by a medical worker.

Hamas released another video in October that showed three women captives denouncing Israeli Prime Minister Benjamin Netanyahu.

How have Israelis reacted to captive-taking?

Family members and thousands of supporters have pressured the Israeli government to prioritise freeing the captives, fearing they could be killed in Israel's assault on besieged Gaza.

A five-day march culminated on Saturday with some 20,000 people on the main Tel Aviv-Jerusalem highway calling on the government to win their freedom.

Netanyahu has vowed to bring the captives home.