JERUSALEM (AP) — Palestinians militants in the Hamas-ruled Gaza Strip fired rockets and mortars into southern Israel on Monday, despite an unofficial truce meant to defuse days of escalating violence.

The Israeli military said 15 projectiles were launched at Israel overnight, most of which fell in open fields and no injuries were reported. Israel retaliated with an airstrike before midnight Sunday that targeted a rocket-launching device.

A Hamas official said Sunday that militant groups in Gaza had agreed a truce would go into effect that evening to end three days of clashes between Israel and Gaza gunmen. Hamas security personnel would enforce the Egypt-brokered agreement, he said, but the continued fire from Gaza undercut his assertion that the cease-fire had the backing of all of Gaza’s armed factions.

The new round of violence began with a deadly attack on Israelis near the Egypt-Israel border on Thursday. That touched off a deadly round of Israeli airstrikes and rocket fire from Gaza.

About 15 Palestinians, most of them gunmen, were killed in the air attacks. Eight Israelis died in the border attack and another was killed by rocket fire.

The sudden flare-up also caused new friction in relations between Israel and Egypt, after Egypt accused Israel of killing five of its security forces while pursuing militants responsible for the frontier ambush on Thursday.

Under pressure from popular anti-Israel sentiment, the Egyptian government at one point threatened to recall its ambassador to Israel. Israel apologized and Egypt recanted.