Amid the celebrations Israeli drones flew overhead, a reminder that while the latest hostilities may have stopped, the underlying conflict is far from over.

The deal – mediated by Egypt – included a promise to end hostilities from both sides and opened the possibility of relaxing border crossings that could ease Israel's five-year air, land and sea blockade on Gaza.

Ending the blockade was one of the key demands of Hamas, Islamic Jihad and other militant factions in Gaza, while Israel had asked for further efforts from Egypt and other countries to prevent Hamas replenishing its weapons supply.

In particular Israel is concerned about the flow of weapons from Libya and Sudan via the network of tunnels from Egypt's territory in the Sinai into Gaza.

If the ceasefire holds for 24 hours, Israel and Hamas have committed to continue the mediated talks on the outstanding border issues, the deal indicates.

Israel's Prime Minister, Benjamin Netanyahu, warned that military action could resume if the ceasefire failed to bring a long-term solution to the rocket fire he said had prompted the army's latest attacks on Gaza.

"But at this time the right thing for the state of Israel is to exhaust this opportunity to obtain a long-term ceasefire," he said.

Against the backdrop of 150 deaths and more than 800 wounded in Gaza, and five deaths and at least 43 wounded in Israel, it is expected the deal will be welcomed by civilians on both sides of the border who are desperate for the violence to end.

In Gaza people in the streets were waving both Fatah and Hamas flags. Policemen hugged each other, while one man watching the celebrations with his family said: "Despite all the losses this is still a victory for Palestinian people - it is not a victory for Hamas, not victory for Egypt but a victory for the Palestinian resistance."

Many feared the bombing of a public bus in Tel Aviv on Wednesday would derail any possibility of a truce, but the mediated talks continued in Cairo and the breakthrough was announced overnight in a joint media conference by Egypt's foreign minister, Mohamed Kamel Amr, and the US Secretary of State, Hillary Clinton.

Sirens were heard across southern Israel, including in the cities of Beersheva, Ashdod and Ashkelon, in the hour before the ceasefire was due to come into effect, Israel Army Radio said. An Israel army spokesman, speaking anonymously, declined to confirm whether the air force had continued to attack targets in Gaza after the announcement.

For the ceasefire to hold "the rocket attacks must end and a broader calm must return", Mrs Clinton said, after days of frantic diplomacy that involved the intervention of the US, the United Nations Secretary, Ban Ki-Moon, the Egyptian President, Mohamed Morsi, and his spy chief, Mohamed Shehata.

"Now we have to focus on reaching a durable outcome that promotes regional stability and advances the security, dignity and legitimate aspirations of Palestinians and Israelis alike," Mrs Clinton said.

The Israeli Defence Forces said in a statement it had ‘‘damaged and destroyed significant elements of Hamas’s strategic capabilities’’ during the conflict, including hundreds of rocket launchers. ‘‘These actions have severely impaired Hamas’s launching capabilities, resulting in a decreasing number of rockets being fired from the Gaza Strip.’’

But Hamas's leader in exile, Khaled Meeshal, said Israel had "failed in its adventure" when it launched its attacks on Gaza.

Medical officials said at least 12 people were killed in Gaza on Wednesday, including a two-year-old boy and a four-year-old girl, as Israel continued its deadly campaign of air strikes in the densely populated coastal strip.

Militants in Gaza had fired nearly 1400 rockets into Israel since the military offensive began last Wednesday, the Israeli Defence Forces said, while Israel had carried out more than 1500 strikes on Gaza during the same period.

Israel launched its current offensive a week ago with the killing of the Hamas military leader Ahmed Jabari, and had massed thousands of soldiers as well as tanks on its southern border, threatening a ground invasion if the rocket strikes continued.

Agence France-Press reported that the deal read: "Israel shall stop all hostilities on the Gaza Strip from land sea and air including incursions and targeting of individuals.

"All Palestinian factions shall stop all hostilities from the Gaza Strip against Israel, including rocket attacks and attacks along the border.

"Opening the crossings and facilitating the movement of people and transfer of goods and refraining from restricting residents' free movement and targeting residents in border areas and procedures of implementation shall be dealt with after 24 hours from the start of the ceasefire."

Despite being warned to stay indoors until the Hamas leadership could assess whether the violence had really ended with the ceasefire, some Gazans took to the streets, driving around flying flags and beeping horns in celebration, while fireworks were fired from some hotels and houses.

The Gaza Strip's streets have mostly been deserted for the past week as civilians stayed indoors for fear of Israeli airstrikes.

With agencies