The Israeli Army lookouts were monitoring Hamas in Gaza across a security fence from a base in southern Israel. As it turned out, Hamas was also watching them.

The four women released by Hamas on Saturday after more than 15 months in captivity in Gaza are “spotters” for the army who were stationed in a small military base about a half-mile from the border.

In the first minutes of the Hamas-led dawn assault on Oct. 7, 2023, gunmen burst through the fence and overran the base, Nahal Oz. Dozens of soldiers were killed, including 15 spotters. The gunmen also dragged seven lookouts — unarmed female conscripts in their late teens — onto trucks and drove them into Gaza. Some were still in their pajamas, some bloodied from wounds.

One of them, Pvt. Ori Megidish, 19, was rescued three weeks later by Israeli forces. Another, Cpl. Noa Marciano, 19, was injured in an Israeli airstrike and then killed by militants inside Gaza’s Shifa hospital, according to the military. Hamas said she died in the bombing.

Four of the remaining five, Naama Levy, Karina Ariev and Daniella Gilboa, who are now all 20, and Liri Albag, 19, were released on Saturday as part of a cease-fire deal providing for the release of scores of Palestinian prisoners, many of them convicted of killing Israelis. A fifth spotter, Agam Berger, is slated to be released in the coming days or weeks under that deal, which came into effect on Jan. 19.

Ms. Levy, Ms. Berger and Ms. Albag were recent recruits who had arrived at the base less than two days before the attack. The Israeli military has not disclosed the rank of the captured soldiers.