Jerusalem, Oct 7 : Israel and the occupied Palestinian territories are reeling from the most serious escalation between the Jewish state and the Islamist group Hamas to date, after a surprise Palestinian attack on the morning of a Jewish holiday led to hundreds of deaths, the seizure of dozens of Israeli hostages, and sparked fears of a regional escalation, media reported. Unverified videos released by Hamas, the militant organisation that seized control of the Gaza Strip in 2007, showed captive young Israelis covered in blood, their hands tied behind their backs and eyes wide with fright as battles between the faction and the Israel Defense Forces (IDF) continued to rage across southern Israel and in the Palestinian enclave on Saturday, The Guardian reported. At least 250 people in Israel were killed, with at least 1,800 injured, according to Israeli officials. The Red Crescent said 92 people had been injured in the West Bank. On Israeli television, family members of the dead, and of dozens of missing people taken hostage by Hamas, wept down phones as they described how their homes and communities had been attacked while families slept. In the Gaza Strip, at least 232 people were killed and 1,650 injured in the retaliatory Israeli airstrikes, sending the area's already crumbling medical infrastructure into chaos. The security situation across Gaza, Jerusalem and the West Bank, volatile at the best of times, has been steadily deteriorating for a year- and-a-half. But no one on either side foresaw the scale and ferocity of what Hamas has dubbed "Operation al-Aqsa Deluge," an unprecedented sea, air and ground offensive by Hamas that has opened a frightening new chapter in the decades-old conflict, The Guardian reported. The Israeli security establishment's failure to foil the attack could reverberate for decades to come, in much the same way as the Yom Kippur war that began 50 years ago this week. Israelis across the centre and south of the country were woken by the thud of missile fire and wailing of air raid sirens from about 7 a.m. on Saturday, the last day of the Jewish high holidays. Simultaneously, an unknown number of Hamas operatives blew up or used bulldozers to tear down several parts of Israel's hi-tech separation fence on the Gaza boundary, from there making their way into neighbouring Israeli towns and villages, The Guardian reported. In the chaos, it is unclear how much land Hamas managed to seize, but by nightfall the IDF estimated there were still 200-300 militants in Israeli territory, and an unknown number of civilians were still barricaded inside their homes, or being held hostage. Israel declared a state of war, scrambling reservist forces and launching massive airstrikes across the Gaza Strip. Clashes between Palestinians and IDF troops were also reported throughout the West Bank and East Jerusalem. Initial reports said that at least one Palestinian had been killed, The Guardian reported. Hamas's operation must have been months, if not years, in the making, and is likely to have involved regional cooperation with Iran, which sponsors both Hamas and the Lebanese militant group, Hezbollah, The Guardian reported. "Today is a game-changer in the conflict. No one is sure why this happened now, but it points to catastrophic failure of every single Israeli institution to do its job," said Dahlia Scheindlin, a political strategist and policy fellow at The Century Foundation. Regional escalation was possible in the coming days, she added. "It's an open question what happens next," she said, The Guardian reported. /IANS