The opening of the border crossings allowed fuel trucks in to supply Gaza's only power plant and increase the availability of electricity, which was down to about eight hours a day.
At least 44 people, 15 of them children, were killed in 56 hours of violence that began when Israeli air strikes hit a senior Islamic Jihad commander.Â
Israel said its action was a pre-emptive strike against an attack the Iranian-backed group had planned.
Hundreds more people were wounded and several houses destroyed in the Gaza Strip.
Palestinian militants fired more than 1000 rockets at Israel, sending residents of southern areas and major cities including Tel Aviv fleeing to shelters.
"The ceasefire is fragile. Any resumption of hostilities will only have devastating consequences for Palestinians and Israelis and make any political progress on key issues elusive," UN Middle East envoy Tor Wennesland told the United Nations Security Council when it met on Monday over the latest violence.
After the fighting ended, both sides sent out a triumphant message.
"All our goals were achieved. The entire senior military command of Islamic Jihad in Gaza was successfully eliminated in three days," Israeli Prime Minister Yair Lapid said in a televised statement.
In a news conference broadcast on the pro-Iranian station Al Mayadeen following the ceasefire late on Sunday, Islamic Jihad leader Ziad al-Nakhala declared: "This is a victory."
Israel, however, saw it as a significant degradation of Islamic Jihad capabilities.
"There's no doubt Islamic Jihad was dealt a serious blow from which it will take time to recover," an Israeli military official said, pointing to the loss of two senior commanders.
Israeli officials also said about 20 fighters were killed by the strikes and large quantities of anti-tank weapons and rocket production and storage facilities were destroyed.
A spokesman for Islamic Jihad in Gaza said the group may have suffered losses to its leadership and fighting strength but it had been able to impose conditions on Israel and maintain unity and cohesion.
Aware of the danger of escalating the conflict, Israel was careful to focus on Islamic Jihad targets to avoid drawing Hamas, the much larger and more powerful militant group that rules Gaza, into the fighting.
Little more than a year after an 11-day war in May 2021 that killed 250 Gazans, Hamas offered some verbal support to its smaller ally but took no action as Israel pursued its air strikes.
