Israel unleashed a wave of airstrikes Friday on Gaza, killing at least 10 people, including a senior militant, according to Palestinian officials. Israel said it targeted the Islamic Jihad militant group in response to an "imminent threat" following the recent arrest of another senior militant.

Hours later, Palestinian militants launched a barrage of rockets as air-raid sirens wailed in Israel and the two sides drew closer to another all-out war. Islamic Jihad claimed to have fired 100 rockets.

Israel and Gaza's militant Hamas rulers have fought four wars and several smaller battles over the last 15 years at a staggering cost to the territory's 2 million Palestinian residents.

A blast was heard in Gaza City, where smoke poured out of the seventh floor of a tall building. Video released by Israel's military showed the strikes blowing up three guard towers with suspected militants in them.

In a nationally televised speech, Israeli Prime Minister Yair Lapid said his country launched the attacks based on "concrete threats."

"This government has a zero-tolerance policy for any attempted attacks - of any kind - from Gaza towards Israeli territory," Lapid said. "Israel will not sit idly by when there are those who are trying to harm its civilians."

He added that "Israel isn't interested in a broader conflict in Gaza but will not shy away from one either."

The violence poses an early test for Lapid, who assumed the role of caretaker prime minister ahead of elections in November, when he hopes to keep the position. He has experience in diplomacy, having served as foreign minister in the outgoing government, but his security credentials are thin.

Hamas also faces a dilemma in deciding whether to join a new battle barely a year after the last war caused widespread devastation. There has been almost no reconstruction since then, and the isolated coastal territory is mired in poverty, with unemployment hovering around 50%.

The Palestinian Health Ministry said a 5-year-old girl and a 23-year-old woman were among those killed in Gaza, without differentiating between civilian and militant casualties. The Israeli military said early estimates were that around 15 fighters were killed. Dozens of people were wounded.

Islamic Jihad said Taiseer al-Jabari, its commander for northern Gaza, was among the dead. He had succeeded another militant killed in an airstrike in 2019.

An Israeli military spokesman said the strikes were in response to an "imminent threat" from two militant squads armed with anti-tank missiles. The spokesman, who briefed reporters on condition of anonymity, said al-Jabari was deliberately targeted and had been responsible for "multiple attacks" on Israel.

Hundreds marched in a funeral procession for him and others who were killed, with many mourners waving Palestinian and Islamic Jihad flags and calling for revenge.

Israeli media showed the skies above southern and central Israel lighting up with rockets and interceptors from Israel's Iron Dome missile-defense system. An explosion was heard in Tel Aviv.

It wasn't immediately clear how many rockets were launched, and there was no immediate word on any casualties on the Israeli side.

Israel continued to strike other targets Friday, including weapon-production facilities and Islamic Jihad positions.

The U.N. special envoy to the region, Tor Wennesland, said he was "deeply concerned."

"The launching of rockets must cease immediately, and I call on all sides to avoid further escalation," he said.

Following the initial Israeli strikes, a few hundred people gathered outside the morgue at Gaza City's main Shifa hospital. Some went in to identify loved ones and emerged later in tears.

"May God take revenge against spies," shouted one, referring to Palestinian informants who cooperate with Israel.

Defense Minister Benny Gantz approved an order to call up 25,000 reserve soldiers if needed while the military announced a "special situation" on the home front, with schools closed and limits placed on activities in communities within 80 kilometers (50 miles) of the border.

Israel closed roads around Gaza earlier this week and sent reinforcements to the border as it braced for a revenge attack after Monday's arrest of Bassam al-Saadi, an Islamic Jihad leader, in a military raid in the occupied West Bank. A teenage member of the group was killed in a gunbattle between the Israeli troops and Palestinian militants.

Hamas seized power in the coastal strip from rival Palestinian forces in 2007. Its most recent war with Israel was in May 2021, and tensions soared again earlier this year following a wave of attacks inside Israel, near-daily military operations in the West Bank and tensions at a flashpoint Jerusalem holy site.

Islamic Jihad leader Ziad al-Nakhalah, speaking to Al-Mayadeen TV network from Iran, said "fighters of the Palestinian resistance have to stand together to confront this aggression." He said there would be "no red lines" and blamed the violence on Israel.

Hamas spokesman Fawzi Barhoum said "the Israeli enemy, which started the escalation against Gaza and committed a new crime, must pay the price and bear full responsibility for it."

Islamic Jihad is smaller than Hamas but largely shares its ideology. Both groups are opposed to Israel's existence and have carried out scores of deadly attacks over the years, including the firing of rockets into Israel. It's unclear how much control Hamas has over Islamic Jihad, and Israel holds Hamas responsible for all attacks emanating from Gaza.

Israel and Egypt have maintained a tight blockade over the territory since the Hamas takeover. Israel says the closure is needed to prevent Hamas from building up its military capabilities, while critics say the policy amounts to collective punishment.

Mohammed Abu Selmia, director of the Shifa hospital, said hospitals faced shortages after Israel imposed a full closure on Gaza earlier this week. He said there were enough supplies and essential drugs to sustain hospitals for five days in normal times, but that with a new round of fighting underway, "they may run out at any moment."

Israel called off an expected fuel delivery for Gaza's sole power plant, which was expected to shut down early Saturday if the fuel did not enter the territory. Even when the plant is running at full capacity, Gazans still endure daily power outages that last several hours.

Earlier Friday, a couple of hundred Israelis protested near the Gaza Strip to demand the return of the remains of two Israeli soldiers held by Hamas.

The protesters were led by the family of Hadar Goldin, who along with Oron Shaul was killed in the 2014 Gaza war. Hamas is still holding their remains, as well as two Israeli civilians who strayed into Gaza and are believed to be mentally ill, hoping to exchange them for some of the thousands of Palestinian prisoners held by Israel.

Israel says there can be no major moves toward lifting the blockade until the soldiers' remains and captive civilians are released. Israel and Hamas have held numerous rounds of Egyptian-mediated talks on a possible swap.

From The Associated Press