Palestinians say a new Israeli airstrike has killed five people from a single family in central Gaza Strip.
Hamas' al-Aqsa Radio reported early Thursday that the dead include parents and their children.
Witnesses in Deir al-Balah town say they heard two explosions followed by the sound of ambulance sirens.
The Palestinian Red Crescent Society says crews are still searching the area.
The latest incident puts the death toll at 31 for Palestinians killed in the worst surge of violence between Israel and Gaza militants in a month. It began when Israel killed a senior Islamic Jihad commander in an airstrike at his house early Tuesday.
Among the dead are 16 militants, a woman and three minors. Ages of those killed in the latest strike are yet to be announced.
The head of the Islamic Jihad says the Palestinian militant group is willing to agree to a cease-fire if Israel accepts certain "conditions."
Ziad al-Nakhalah told Lebanese Al-Mayadeen TV Wednesday that Egypt was brokering truce talks to end the worst round of fighting between Israel and Gaza militants in months.
He specified three conditions, foremost a commitment by Israel to stop targeted killing of Palestinian leaders and senior militants.
Israel killed a senior Islamic Jihad commander in an airstrike on his Gaza City home on Tuesday, sparking retaliatory rocket fire from Gaza and Israeli airstrikes have killed 26 Palestinians, including 16 militants.
Al-Nakhalah also demanded Israel stop shooting Palestinians at weekly protests along Gaza's frontier, and honor the indirect understandings with Gaza's Hamas rulers to ease the territory's economic hardships.
The U.N. Mideast envoy says negotiators are "working to urgently de-escalate" fighting between Israel and Palestinian militants in the Gaza Strip.
Nickolay Mladenov said in a statement Wednesday during a trip to Cairo that he was "very concerned about the ongoing and serious escalation" of hostilities.
Mladenov was to meet with Egyptian President Abdel-Fattah el-Sissi as part of efforts to broker a ceasefire.
The heaviest round of fighting in months was triggered early Tuesday by Israel's targeted killing of a senior Islamic Jihad commander in Gaza.
Israel's military says Islamic Jihad has since fired 250 rockets from Gaza into Israel.
The death toll from Israeli airstrikes in Gaza has risen to 23 Palestinians, including a 7-year-old boy and two other minors.
The U.N. diplomat condemned the Islamic militant group's attacks as "absolutely unacceptable."
Egyptian officials say U.N. Mideast envoy has arrived in Cairo in efforts to deescalate the worst escalation between Israel and Gaza militants in recent months.
The officials say that Nickolay Mladenov landed on Wednesday from Tel Aviv and is scheduled to meet President Abdel-Fattah el-Sissi.
The officials spoke on condition of anonymity because they were not authorized to brief the media.
Egypt has stepped up communication with Israel and the militants in Gaza, and has "opened channels" with the U.S. and the European Union. Cairo often acts as a mediator between Israel and Gaza militants, and brokered a cease-fire deal in May.
The latest bout of violence started after a pre-dawn Israeli airstrike in Gaza killed a senior Islamic Jihad commander on Tuesday. The militants in Gaza responded with barrages of rockets fired into Israel.
-Samy Magdy in Cairo;
Gaza's Health Ministry says two more Palestinians have been killed by ongoing Israeli airstrikes, bringing the death toll in the escalation over the past two days to 18.
Among the dead are 11 confirmed Islamic Jihad militants, including Bahaa Abu el-Atta, a senior Islamic Jihad commander whose killing in a pre-dawn airstrike at his Gaza City home on Tuesday sparked the new round violence.
Among the latest casualties were a father and two sons whose identities remain unclear. Mobile video shows they were hit while travelling on a motorbike.
The Israeli military says more than 250 rockets have been fired since Tuesday in the heaviest round of fighting in months. Gaza's Hamas leaders have stayed out of the fray.
Prime Minister Benjamin Netanyahu says Israel is prepared to keep pounding Islamic Jihad militants in Gaza as long as rocket fire continues.
Netanyahu said on Wednesday at the start of a special Cabinet meeting that the Iranian-backed militant groups better internalize Israel's determination before it is too late for them.
Netanyahu says militants have a choice: "Either stop these attacks or absorb more and more blows."
Israeli airstrikes have killed 16 Palestinians since Tuesday, nearly all Islamic Jihad militants.
The Israeli military says more than 250 rockets have been fired at Israeli communities since the violence erupted following an Israeli airstrike that killed a senior Islamic Jihad commander accused of being the mastermind of attacks. It marks the heaviest round of fighting in months.
Israel's new defense minister says the country will not hesitate to target more Gaza militants.
Naftali Bennett's comments on Wednesday were his first as Israel's new defense minister.
He says Israel is sending a clear message to its enemies: "Whoever plans to hard us during the day, will never be safe to make it through the night."
The message comes a day after a pre-dawn strike killed a senior Islamic Jihad commander in Gaza and triggered hundreds of rockets fired toward Israel, the heaviest fighting in months between Israel and the Iranian-backed militant group that's even more hard-line than Gaza's Hamas rulers.
Bennett took office on Tuesday to fortify Prime Minister Benjamin Netanyahu's political base. Bennett has long advocated tougher action against Palestinian militants.
Gaza's Health Ministry says four more Palestinians have been killed in Israeli airstrikes across the coastal enclave.
The latest killings raised on Wednesday the overall death toll to 16, most of them militants.
Ten Palestinians were killed in Gaza when the latest round of violence erupted early on Tuesday after an Israeli airstrike hut the home of a senior Islamic Jihad commander, killing him alongside his wife.
The ministry also says 50 Palestinians have been wounded since Tuesday.
Gaza officials say new Israel airstrikes have killed two militants, raising the death toll to 12 since the latest escalation erupted.
The Islamic Jihad says two of its fighters were targeted Wednesday, as rocket fire into Israel resumed along with Israeli retaliation after a brief overnight lull. Nearly all the casualties were Islamic Jihad members.
The military says some 220 rockets have been fired since Tuesday, following an Israel strike that killed a senior Islamic Jihad commander.
It's the heaviest fighting in months between Israel and the Iranian-backed militant group that's even more hard-line than Gaza's Hamas rulers.
But Hamas has yet to join the fray, a possible sign the fighting could be brief. With Gaza's economy in tatters, Hamas appears to have little desire for another round of fighting.
Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.