Hamas has launched a manhunt in the Gaza Strip following the mysterious killing of one its military commanders, which the group says was carried out by Israeli assassins.
The lslamist militant organisation has placed the isolated Mediterranean enclave of Gaza on lock down as it hunts for the killers of Mazen Faqha, a Hamas leader who was shot dead on Friday.
While it searches for the alleged Israeli hit squad - and any Palestinian collaborators - Hamas is preventing men younger than 45 from leaving Gaza and imposed a media blackout on details of its investigation.
Israel has neither confirmed nor denied any role in the killing but Faqha's death has raised tensions in Gaza and the Israeli military is bracing for potential retaliation from Hamas.
“Israel decided to change the rules of the game, and we accept the challenge,” said Khaled Meshal, the head of Hamas's political wing.
The 38-year-old Faqha was found shot dead on Friday in his home in Gaza City. Hamas said the killers had used silencers on their weapons and placed the blame on the Mossad, Israel's foreign intelligence service.
If the killing was carried out by Israel it would be a dangerous and provocative mission as sending assassins into the heart of Gaza is far riskier than carrying out a drone strike.
Alon Eviatar, a former Israeli military intelligence officer, said it was possible Faqha was killed by Palestinian political rivals but that judging from the professionalism of the killing it was more likely the work of Israel.
"For five days have Hamas have been searching and they have not found any answers. But they cannot leave this issue without taking any action," Mr Eviatar said.
Israel has imposed a blockade on Gaza since 2007 and severely limited Palestinian's ability to leave the coastal strip. But as part of their search, Hamas has stopped men under 45 from leaving even if they have a permit.
Hamas also forbid Palestinian media outlets in Gaza from reporting on the investigation or quoting Israeli media sources. “The goal of the enemy’s media is clear. They want to disrupt our inquiry measures. They don’t want us to discover those criminals involved in the assassination’s crime,” the group said.
Faqha was originally from the West Bank and was jailed by Israel in 2003 for an alleged terror plot. He was released as part of a prisoner exchange in 2011 but a condition of his freedom was that he could only live in Gaza and not return to the West Bank.