Israel unleashed new air strikes on Gaza early on Tuesday, hitting the high-rise home of a Hamas field commander and two border tunnels dug by militants, as Hamas and other armed groups fired dozens of rockets toward Israel.
It was an escalation sparked by weeks of tensions in contested Jerusalem.
Since the cross-border fighting erupted on Monday evening, 24 Palestinians – including nine children – have been killed in Gaza, most by air strikes, Gaza health officials said.
The Israeli military said 15 of the dead were militants.
During the same period, Gaza militants fired more than 200 rockets towards Israel, injuring six Israeli civilians.
This was preceded by hours of clashes on Monday between Palestinians and Israeli security forces, mainly in Jerusalem but also across the West Bank.
More than 700 Palestinians were hurt, nearly 500 of whom needed hospital treatment.
The current violence, like previous rounds, was fuelled by conflicting claims over Jerusalem, home to major holy sites of Islam, Judaism and Christianity. The rival national and religious narratives of Israelis and Palestinians are rooted in the city, making it the emotional core of their long conflict.
In the past, cross-border fighting between Israel and Hamas, the group that rules Gaza, would typically end after a few days, often helped by behind-the-scenes mediation by Qatar, Egypt and others. It was not clear if that trajectory would be repeated this time.
Israeli Prime Minister Benjamin Netanyahu warned on Monday that fighting could “continue for some time”.
Spokesman Lieutenant Colonel Jonathan Conricus said on Tuesday that the Israeli military is in “the early stages” of strikes against Gaza targets which were planned well in advance.
The escalation comes at a time of political limbo in Israel.
Mr Netanyahu has been acting as a caretaker prime minister since an inconclusive parliament election in March. He tried and failed to form a coalition government with his hardline and ultra-Orthodox allies, and the task was handed to his sworn political rivals last week.
One of those rivals is Israel’s defence minister, who is overseeing the Gaza campaign. It is not clear if and to what extent the toxic political atmosphere is spilling over into military decision-making, though the rival camps have unanimously expressed support for striking Hamas hard.
The tensions in Jerusalem coincided with the start of the Muslim fasting month of Ramadan in mid-April.
Critics say heavy-handed police measures helped stoke nightly unrest, including a decision to temporarily seal off a popular night-time gathering spot where Palestinian residents would meet after evening prayers. Another flashpoint was Jerusalem’s Sheikh Jarrah neighbourhood where dozens of Palestinians are under threat of eviction by Jewish settlers.
Over the weekend, confrontations erupted at the Al-Aqsa Mosque compound in east Jerusalem, which was captured and annexed by Israel in the 1967 Middle East war. The compound, located in Jerusalem’s Old City, is the third holiest site of Islam and the holiest site of Judaism.
For four successive days, Israel police fired tear gas, stun grenades and rubber bullets at Palestinians in the compound who hurled stones and chairs. Hundreds of Palestinians were injured as well as two dozen officers. At times, police fired stun grenades into the carpeted mosque.
On Monday evening, Hamas began firing rockets from Gaza, setting off air raid sirens as far as Jerusalem, after giving Israel a deadline to withdraw Israeli security forces from the compound. From there on, the escalation was rapid.
Lt Col Conricus said Gaza militants fired more than 200 rockets at Israel, with about one-third falling short and landing in Gaza.
The army said a rocket landed a direct hit on a seven-storey apartment block in the coastal Israeli city of Ashkelon. Photos and videos from the scene showed a large blast hole on the side of the building.
Israeli paramedic service Magen David Adom said it treated six people injured in the rocket strike. Two were take to hospital.
Lt Col Conricus said the military hit 130 targets in Gaza, including the high-rise home of a Hamas field commander and two tunnels militants were digging under the border with Israel.
In all, Israel killed 15 militants, he said, including some tunnel diggers.
He said Israel’s new system of concrete barriers and electronic sensors, intended to thwart tunnel digging, has been operational for the past six months and has proven itself.
He did not address Gaza Health Ministry reports that nine children were among 24 Palestinians killed overnight.
In Gaza, most of the deaths were attributed to air strikes. However, seven were members of one family, including three children, who died in a mysterious explosion in the northern Gaza town of Beit Hanoun. It was not clear if the blast was caused by an Israeli air strike or errant rocket.
More than 100 Gazans were injured in the air strikes, the Health Ministry said.
In one sign of escalation, an Israeli missile hit the upper floors of an apartment building in the Shati refugee camp on the edge of Gaza City early on Tuesday, killing two men and a woman inside, according to health officials.
Israel had struck scores of Gaza homes in its 2014 war with Hamas, arguing that it was aiming at militants, but also killing many civilians. The practice drew broad international condemnation at the time.