TEL AVIV, Israel. Israeli soldiers engaged in fierce battles with Hamas fighters in the streets of southern Israel on Sunday, as retaliation strikes rocked Gaza, while in northern Israel, an exchange of fire with Lebanon’s Hezbollah raised concerns of a broader conflict.

More than 24 hours after an unprecedented surprise attack from Gaza, the situation remained volatile. Hamas militants, supported by a barrage of thousands of rockets, breached Israel’s security barrier and wreaked havoc in nearby communities. They took hostages, including women, children, and the elderly, likely with the intention of using them as bargaining chips for the release of Palestinian prisoners held by Israel. Tragically, hundreds of lives have been lost on both sides.

The high death toll, multiple captives, and a delayed response exposed a significant intelligence failure, challenging the long-held belief that Israel maintains surveillance throughout the densely populated territory it has controlled for decades.

Israeli Prime Minister Benjamin Netanyahu declared that the country was at war and promised to extract a heavy price from its adversaries. Hamas leaders, on the other hand, indicated readiness for further escalation.

A pressing question now is whether Israel will launch a ground assault into Gaza, a move that has historically resulted in heightened casualties. Netanyahu vowed that Hamas would face an “unprecedented price,” but he cautioned that “This war will take time. It will be difficult.”

Civilians have paid a devastating toll for the violence on both sides. Israeli media, citing rescue service officials, reported at least 300 casualties in Israel, including 44 soldiers, while Gaza officials reported 313 deaths. An Israeli official stated that the military had killed 400 militants and detained dozens more.

Israeli television featured heart-wrenching accounts from the relatives of captive or missing Israelis who pleaded for assistance amid uncertainty about their loved ones’ fate. In Gaza, residents fled homes near the border to evade Israeli airstrikes, seeking refuge deeper inside the territory after receiving warnings in Arabic from the Israeli military.

In neighboring Egypt, a policeman fatally shot two Israeli tourists and an Egyptian at a tourist site in Alexandria, according to the Interior Ministry. Although Egypt established peace with Israel decades ago, anti-Israel sentiment remains high, particularly during episodes of Israeli-Palestinian violence.

The escalation on Israel’s northern border also raised concerns of Hezbollah’s involvement, a formidable enemy of Israel backed by Iran and believed to possess tens of thousands of rockets. Hezbollah fired dozens of rockets and shells at three Israeli positions in a disputed area along the border on Sunday, prompting Israel’s military to respond with armed drones. Two children sustained minor injuries from broken glass on the Lebanese side.

Rear Adm. Daniel Hagari, an Israeli military official, reported that the situation on the northern border had calmed following the exchange. However, he noted that fighting persisted in the south, with ongoing hostage situations.

Troops were deployed to every community near the Gaza frontier, where they intended to evacuate all civilians and search for militants. “We will go through every community until we kill every terrorist that is in Israeli territory,” Hagari declared. In Gaza, he added, “every terrorist located in a house, all the commanders in houses, will be hit by Israeli fire. That will continue escalating in the coming hours.”

Hamas claimed that it had continued to send forces and equipment into “a number of locations inside our occupied territories,” referring to Israel. Hamas-affiliated media reported the death of the son of Nizar Awadallah, a senior political official. However, the group had not reported any senior members being captured, killed, or wounded.

Saturday’s surprise attack was the deadliest on Israel in decades. In a shocking assault, Hamas gunmen used explosives to breach the Gaza border fence, then crossed into Israel using motorcycles, pickup trucks, paragliders, and speed boats along the coast. They reached as many as 22 locations outside the Gaza Strip, including towns up to 24 kilometers (15 miles) from the Gaza border, while Hamas unleashed a barrage of rockets at Israeli cities.

Lt. Col. Richard Hecht, an Israeli military spokesman, expressed the profound tragedy of the situation, with numerous casualties, including children and families, in Israel. Israeli media reported over 300 deaths and 1,500 wounded in Saturday’s attack. Hamas fighters took an undisclosed number of civilians and soldiers hostage into Gaza, leading to anxious Israelis seeking information about their missing relatives.

Israel struck 426 targets in Gaza, according to the military, resulting in the destruction of residential buildings in massive explosions. Among the 313 killed in Gaza were 20 children, and nearly 2,000 people were wounded, according to the Palestinian Health Ministry. UNRWA, the United Nations agency for Palestinians, reported that over 20,000 Palestinians fled the Gaza border region to seek refuge in U.N. schools.

In a televised address on Saturday night, Israeli Prime Minister Benjamin Netanyahu pledged to use all available strength to eliminate Hamas’ capabilities. He urged Gaza residents to leave immediately, even though they had no means to escape the tiny, overcrowded Mediterranean enclave. Gaza’s 2.3 million people have endured a border blockade, enforced to varying degrees by Israel and Egypt, since Hamas militants seized control in 2007.

In Gaza, much of the population was plunged into darkness on Saturday night as Israel cut off electricity and halted the supply of power, fuel, and other goods to the territory. Hamas stated that it had prepared for a protracted battle, emphasizing their readiness for all scenarios, including all-out war.

Israel has a history of engaging in heavily lopsided exchanges to secure the release of captive Israelis. The military confirmed that a “substantial” number of Israelis were abducted on Saturday but did not provide a precise figure.

An Egyptian official revealed that Israel sought assistance from Cairo to ensure the safety of the hostages. Egypt’s intelligence chief had contacted Hamas and the smaller but more radical Islamic Jihad group, which also participated in the incursion, to gather information. Egypt has frequently mediated between the two sides in the past.

While Egypt explored the possibility of a ceasefire with both parties, the official reported that Israel was not receptive to a truce “at this stage.”

Hamas’ military wing leader, Mohammed Deif, attributed the assault, named “Operation Al-Aqsa Storm,” to the 16-year blockade of Gaza and recent incidents that had heightened Israeli-Palestinian tensions. Over the past year, Israel’s far-right government increased settlement construction in the occupied West Bank, settler violence displaced hundreds of Palestinians, and tensions flared around the Al-Aqsa mosque, a contentious holy site in Jerusalem.

U.S. President Joe Biden expressed solidarity with Israel, asserting the U.S. “stands with the people of Israel in the face of these terrorist assaults” and emphasized Israel’s right to self-defense.

AP contributed to this report.