Gaza Strip ? Gaza’s warring factions began to hold their fire Tuesday as a truce took effect across the volatile territory and brought hopes for an end to the infighting that has left 36 people dead in five days.

But the killing of a Hamas militant by rival Palestinians – combined with an Israeli airstrike on a smuggling tunnel following a suicide bombing – underscored the fragility of any lull in Gaza’s bloodshed.

Palestinian Prime Minister Ismail Haniyeh of Hamas called for a total halt to the violence.

“The past few days were difficult, and everyone paid in blood,” he said in Gaza. “Everyone is facing a difficult test; either we maintain this calm … or everything collapses again, and then everyone will be held responsible.”

Previous truces between Hamas and Fatah militants in Gaza have quickly collapsed into new fighting, and it appeared unlikely the two sides would comply with all the terms of the current agreement, such as handing over all those involved in killings and abductions.

Late Tuesday, the two sides began releasing hostages – fighters kidnapped over the past week – both sides said.

Hamas and Fatah gunmen have used prior lulls to prepare for more fighting.