The Israeli army attacked the Gaza Strip for a third day last night, killing two people, the official Palestinian Authority news agency said, in a test of the fragile ceasefire agreement.

One Palestinian was killed by Israeli shelling, while another was shot and killed by Israeli forces, WAFA reported today. The Israeli military did not immediately respond to a Reuters request for comment.

A third Palestinian succumbed to injuries sustained in an earlier Israeli shelling, the news agency reported.

The US-brokered truce, which left unresolved issues such as the disarmament of Hamas and a timetable for Israel’s withdrawal from the Gaza Strip, has been tested by periodic outbreaks of violence since it took effect three weeks ago.

Between Tuesday and Wednesday, Israel retaliated for the death of an Israeli soldier with shelling that, according to Gaza health authorities, killed 104 people. Israel said Wednesday it remains committed to the ceasefire, despite the retaliation.

Israel maintains that the soldier was killed in an attack by gunmen on territory inside the “yellow line” where its troops were withdrawn under the ceasefire. The Palestinian Islamist organization Hamas denies the accusation.

At the same time, Hamas handed over the remains of two Israeli hostages yesterday. As part of the cease-fire agreement, Hamas released all hostages alive and held in Gaza in exchange for nearly 2,000 Palestinian prisoners and detainees, while Israel agreed to withdraw its troops, end its offensive and increase humanitarian aid.

Hamas also agreed to hand over the remains of all 28 hostages not found alive in exchange for 360 Palestinian fighters killed in the war. After yesterday’s release, he has handed over at least 17 bodies.

Hamas has said it will take time to locate and recover the bodies of the remaining hostages. Israel accuses Hamas of violating the ceasefire by delaying the handover of the bodies.