JERUSALEM — The Israeli military escalated its campaign against the Hamas militant group in Gaza late Thursday as artillery, tanks and war planes combined in a withering assault on the Palestinian enclave, and the Israeli military readied at least three brigades of troops for action, raising the prospect of a ground invasion.

Just after midnight, the Israeli military announced that air and ground forces were attacking in the Gaza Strip, but the extent of the operation remained unclear. A military spokesperson initially said, "There are ground troops in Gaza.” But another spokesman for the Israel Defense Forces later issued a “clarification,” saying, “There are currently no IDF ground troops inside the Gaza Strip.”

Residents of Gaza City said intense, almost continuous airstrikes began to pound the northern Gaza Strip around midnight in the most intense attacks over four nights of aerial bombardments and lasted for about half an hour.

Here’s what to know:

  • Israeli tanks, artillery and war planes launched the most intense assault on Gaza yet during four nights of bombardment.
  • Gazans awakened on a usually joyous Eid al-Fitr holiday to devastation caused by Israeli airstrikes.
  • Unrest has broken out in towns across Israel as bands of Jewish and Arab citizens clash.
  • Hamas has fired hundreds of rockets at Israel since Wednesday night.

For most of Thursday, the air war between Israelis and Palestinians had raged unabated with casualties continuing to climb on both sides amid rocket fire and airstrikes.

Violence also continued to spread within Israel as officials braced for a fourth night of street unrest that has seen Arab Israelis and right-wing Jewish Israelis fight one another in towns across the country. Israeli politicians from across the ideological spectrum condemned attacks by “vigilantes” from both sides, and commentators warned that the communal upheaval may be harder to stop than the military conflict between Israel and the Hamas militant group, which governs Gaza.

Soon after sunset on Thursday, clashes between Jewish and Arab Israelis had resumed in several cities.

The reciprocal bombardment has taken a mounting toll on transportation and other infrastructure in both Israel and Gaza. Under a rain of more than 1,700 rockets fired from Gaza in recent days, Israel’s Ben Gurion Airport, the country’s main link to the outside world, closed indefinitely to incoming flights on Thursday. Israeli media reported that rockets struck Israel’s secondary Ramon Airport, where flights had been diverted.

In Gaza, damage to power lines cut daily electricity in some parts of the enclave to around three hours.

In Gaza, residents awoke on the normally joyous Eid al-Fitr holiday to pillars of smoke rising from sites bombed by the Israeli military. In the midst of the worst attacks in seven years, streets that would normally bustle with families going to pay holiday visits were quiet.

Gaza’s Health Ministry said 109 Palestinians, including 28 children, had been killed by Thursday night. It said 621 people have been wounded.

On some blocks, displaced residents picked through the rubble of destroyed homes. In northern Gaza City on Thursday morning, Zaher Sbieh pulled two stuffed sheep from what had been a five-story apartment building. They would be a nice surprise for his four children, who are now staying with family in Jabaliya.

The building was demolished by an airstrike Wednesday afternoon, 90 minutes after Sbieh’s brother, who lived in an apartment next door, got an urgent call: Get out now. The call was from an Israeli military officer, Sbieh said. The officer said the building next door was a target. The brothers and their families joined the panicked rush down the stairs as the building emptied. When he returned later that evening, it was gone.

“I lost everything, my clothing, books, laptops, photo albums,” said Sbieh, 48, who runs a youth and community advocacy group. “I evacuated with the clothes I’m wearing.”

Mohammad Qadada, 31, said that the Israeli demolition of the 13-story Hanadi building, which houses his IT company’s offices, has caused him, for the first time, to consider leaving the Gaza Strip.

“I always said, ‘I can’t leave my country, I can’t leave my country.' But now, I can’t be in my country,” said Qadada, who plans to try obtaining Swedish citizenship through his Swedish-born wife.

“We lived through the first war in Gaza in 2008; it was the worst one. But, for me, the past two days are worse than ever because I have a family. When you look at your son who is crying from the bombing, my wife’s tears, my mother’s tears, it is exhausting,” he said.

In Israel, where seven people — six civilians and one soldier — have been killed since the rocketing began on Monday, families were also counting their losses. The slain civilians include a teenage girl and a young boy who died Wednesday evening from an earlier rocket strike on the family’s bomb shelter in Sderot near the border with Gaza, local media reported.

Late on Thursday, Lebanese media reported rockets being fired from southern Lebanon toward Israel. Israel’s military said three rockets had landed in the Mediterranean Sea. A media liaison for the Lebanese militant group Hezbollah, which has repeatedly battled Israeli forces, declined to comment on the attack, and Israeli media reported that the rockets had been fired by Palestinians in Lebanon.

The prospect of even fiercer fighting seemed to grow Thursday as two Israeli infantry brigades and an armored one readied for ground operations, according to Israeli military spokesman Lt. Col. Jonathan Conricus. Israeli troops last entered Gaza en masse during a two-month war in 2014, when more than 2,200 Gazans were killed.

The Palestinians were also talking tough. “We have much more to give,” a Hamas spokesman known as Abu Obaida said in a televised statement. “The decision to hit Tel Aviv, Dimona and Jerusalem is easier for us than drinking water. Your technology and assassinations don’t scare us.”

Diplomats from the Middle East, Europe and the United States scrambled to broker a cease-fire before the conflict took another devastating turn. Arabic media reported that an Egyptian delegation arrived in Tel Aviv on Thursday. Hady Amr, the U.S. deputy assistant secretary of state for Israel and Palestinian affairs, was also on his way, the State Department said.

In remarks, Secretary of State Antony Blinken made clear he places more blame on Hamas, saying there is a “fundamental difference between a terrorist organization in Hamas that is indiscriminately targeting civilians and Israel, which is defending itself.” Blinken and President Biden’s refrain that Israel has a right to defend itself has come under criticism from several liberal American lawmakers.

Even as Israeli troops were readied for action in Gaza, Prime Minister Benjamin Netanyahu announced he would separately deploy the military in restive Israeli towns to quell the “anarchy.” He said he has ordered police to adopt “emergency powers” and intends to “bring in military forces according to the existing law, and we will pass an additional law if necessary.”

“What is happening in Israel’s cities over the past few days is unacceptable,” Netanyahu said on Twitter of the worst Jewish-Arab violence inside Israel in decades. “We have seen Arab rioters set fire to synagogues and vehicles and attack police officers. They are attacking peaceful and innocent citizens.”

The prime minister also alluded to video footage of a group of Jewish nationalists dragging a man whom they believed to be Arab out of his car and beating him in the central city of Bat Yam. “Nothing justifies this and I will tell you that nothing justifies the lynching of Jews by Arabs and nothing justifies the lynching of Arabs by Jews.”

Not long after he spoke, police reported two people injured in a shooting in the central city of Lod, according to the Associated Press. The mixed Arab-Jewish town has become a center of unrest following the fatal shooting of an Arab Israeli man this week, and it remains under heavy police patrol and nighttime lockdown.

Some 400 people were arrested overnight Wednesday in riots throughout the country, according to Israel Police spokesman Micky Rosenfeld. He said 36 officers were injured. Officials said they expected the clashes to continue into Friday, when thousands of Muslim worshipers are expected at Jerusalem’s al-Aqsa Mosque.

The current conflict was triggered after clashes earlier this month in Jerusalem among Palestinians, Israeli police and right-wing Jews. Tensions have been running high, in part, because of efforts by Israeli settlers to evict several Palestinian families from their homes in the Sheikh Jarrah neighborhood of East Jerusalem.

Rubin reported from Tel Aviv. Hazem Balousha in Gaza, Sarah Dadouch in Beirut and John Hudson in Washington contributed to this report.