The long-awaited ceasefire between Israel and Hamas has finally come into effect, behind schedule by almost three hours, during which Israeli forces continued to strike Gaza, blaming the militant group’s failure to release the names of the hostages due to be released on Sunday.

The ceasefire finally started at 9.15am GMT, after Hamas posted the names of the three hostages on its social media channels.

The Hamas-run civil defence agency said eight people had been killed in the Israeli strikes on the Gaza Strip during the hours after the ceasefire was supposed to take effect. Three Palestinians were killed in eastern Gaza City by Israeli drones, medics in the territory said on Sunday. The Israeli military said that it had struck “terror targets” in northern and central Gaza, and it would continue to attack as long as Hamas did not meet its demands.

Hamas named the three female hostages as Romi Gonen, 24, Emily Damari, 28, and Doron Steinbrecher, 31. They will be released through the Red Cross, in return for 30 Palestinian prisoners each.

The ceasefire opens the way to a possible end to a 15-month war that has upended the Middle East. But the delay was a reminder of how fragile the process is likely to be.

Israeli forces had started withdrawing from areas in Rafah, Gaza to the Philadelphi corridor along the border between Egypt and Gaza, pro-Hamas media reported early on Sunday.

Israel’s military warned Gaza residents not to approach its troops or move around the Palestinian territory before the ceasefire deadline, adding when movement is allowed “a statement and instructions will be issued on safe transit methods”.

The three-stage ceasefire agreement followed months of on-off negotiations brokered by Egypt, Qatar and the United States, and came just before the inauguration of Donald Trump as president on Monday.

Its first stage will last six weeks, during which 33 of the remaining 98 hostages – women, children, men over 50, the ill and wounded – will be released in return for almost 2,000 Palestinian prisoners and detainees.

The prisoners include 737 male, female and teenage inmates, some of whom are members of militant groups convicted of attacks that killed dozens of Israelis, as well as hundreds of Palestinians from Gaza in detention since the start of the war.

After Sunday’s hostage release, according to the lead US negotiator, Brett McGurk, the accord calls for four more female hostages to be freed after seven days, followed by the release of three further hostages every seven days thereafter.

During the first phase the Israeli army will pull back from some of its positions in Gaza and Palestinians displaced from areas in northern Gaza will be allowed to return.

The US president, Joe Biden’s team worked closely with Trump’s Middle East envoy, Steve Witkoff, to push the deal over the line.

As his inauguration approached, Trump had repeated his demand that a deal be done swiftly, warning repeatedly that there would be “hell to pay” if the hostages were not released.

But what will come next in Gaza remains unclear, in the absence of a comprehensive agreement on the postwar future of the territory, which will require billions of dollars and years of work to rebuild.

And although the stated aim of the ceasefire is to end the war entirely, it could easily unravel.

Hamas, which has controlled Gaza for almost two decades, has survived despite losing its top leadership and thousands of fighters.

Israel has vowed it will not allow Hamas to return to power and has cleared large stretches of ground inside Gaza, in a step widely seen as a move towards creating a buffer zone that will allow its troops to act freely against threats in the territory.

In Israel, the return of the hostages may ease some of the public anger against Netanyahu and his rightwing government over the 7 October security failure that led to the deadliest single day in the country’s history.

But hardliners in his government have already threatened to quit if the war on Hamas is not resumed, leaving him pressed between Washington’s desire to see the war end, and his far-right political allies at home.

The national security minister, Itamar Ben-Gvir’s far-right party, Otzma Yehudit announced on Sunday morning that it had officially left the governing coalition.