Hamas militants freed three male hostages held for more than a year in the Gaza Strip on Saturday and Israel released 183 Palestinian prisoners from Israeli jails in the fourth such exchange of a ceasefire deal that has halted 15 months of intense fighting.

It is believed that at least two of the six American hostages still held in Gaza are alive — Sagui Dekel-Chen, 35, who grew up in Bloomfield, Connecticut, and Edan Alexander, 19, from Tenafly, New Jersey. Four other Americans are believed to have been killed in captivity.