Jerusalem. Hamas militants fired thousands of rockets and sent dozens of fighters into Israeli towns near the Gaza Strip in an unprecedented surprise early morning attack during a major Jewish holiday Saturday, killing dozens and stunning the country. Israel said it is now at war with Hamas and launched airstrikes in Gaza, vowing to inflict an “unprecedented price.”

In an assault of startling breadth, Hamas gunmen rolled into as many as 22 locations outside the Gaza Strip, including towns and other communities as far as 15 miles (24 kilometers) from the Gaza border. In some places, they roamed for hours, gunning down civilians and soldiers until Israel's military mustered a response. Even well after nightfall, gunbattles continued in some locations.

Israel’s national rescue service said at least 100 people were killed and hundreds wounded, making it the deadliest attack in Israel in years. An unknown number of Israeli soldiers and civilians were also taken captive and brought into Gaza, an enormously sensitive issue for Israel. Army spokesman Daniel Hagari said militants were also holding hostages in standoffs in two towns.

At least 198 people in the Gaza Strip have been killed and at least 1,610 wounded in Israel’s retaliation, the Palestinian Health Ministry said. After nightfall, airstrikes intensified, flattening several residential buildings in giant explosions, including a 14-story tower that held dozens of apartments as well as Hamas offices in central Gaza City. Israeli fired a warning just before, and the number of casualties was not immediately known. Soon after, Hamas fired a barrage of rockets into central Israel, hitting four cities, including Tel Aviv and a nearby suburb, where two people were seriously injured.

The conflict threatened to spiral dramatically further with Israel’s warnings of greater retaliation. Previous conflicts between Israel and Gaza’s Hamas ruler brought widespread death and destruction in Gaza and days of rocket fire on Israeli towns. The mix is potentially more volatile now, with Israel’s far-right government stung by the security breach and with Palestinians in despair over a never-ending occupation.

The strength, sophistication and timing of the Saturday morning attack shocked Israelis. Hamas fighters used explosives to break through the border fence enclosing the long-blockaded Mediterranean territory, then crossed with motorcycles, pickup trucks, paragliders and speed boats on the coast.

Bodies of dead Israeli civilians and Hamas militants were seen on streets of Israeli towns. Associated Press photos showed an abducted elderly Israeli woman being brought back into Gaza on a golf cart by Hamas gunmen and another woman squeezed between two fighters on a motorcycle. Images on social media showed fighters parading what seemed to be captured Israeli military vehicles through Gaza streets and a dead Israeli soldier being dragged and trampled by crowd of Palestinians.

“We are at war,” Israeli Prime Minister Benjamin Netanyahu said in a televised address, declaring a mass army mobilization. “Not an ‘operation,’ not a ‘round,’ but at war.”

“The enemy will pay an unprecedented price,” he added, promising that Israel would “return fire of a magnitude that the enemy has not known.”

The shadowy leader of Hamas’ military wing, Mohammed Deif, said the assault was in response to the 16-year blockade of Gaza, Israeli raids inside West Bank cities over the past year, violence at Al Aqsa -- the disputed Jerusalem holy site sacred to Jews as the Temple Mount -- increasing attacks by settlers on Palestinians and growth of settlements.

“Enough is enough,” Deif, who does not appear in public, said in the recorded message. He said the morning attack was only the start of what he called “Operation Al-Aqsa Storm” and called on Palestinians from east Jerusalem to northern Israel to join the fight. “Today the people are regaining their revolution.”

The Hamas incursion on Simchat Torah, a normally joyous day when Jews complete the annual cycle of reading the Torah scroll, revived painful memories of the 1973 Mideast war practically 50 years to the day, in which Egypt and Syria launched a surprise attack on Yom Kippur, the holiest day of the Jewish calendar, aiming to take back Israeli-occupied territories.

Comparisons to one of the most traumatic moments in Israeli history sharpened criticism of Netanyahu and his far-right allies, who had campaigned on more aggressive action against threats from Gaza. Political commentators lambasted the government over its failure to anticipate what appeared to be a Hamas attack unseen in its level of planning and coordination.

Asked by reporters how Hamas had managed to catch the army off guard, Lt. Col. Richard Hecht, an Israeli army spokesman, replied, “That’s a good question.”

The abduction of Israeli civilians and soldiers also raised a particularly thorny issue for Israel. Israel has a history of making heavily lopsided exchanges in order to bring captive Israelis home.

Their number was not immediately known. Videos released by Hamas appeared to show at least three Israelis captured alive, and AP photos showed at least three civilians brought in Gaza, including the two women. Israeli television showed images of a young man stripped down to his pants being led on foot in a chokehold and reported that elderly women with dementia as well as workers from Thailand and the Philippines were among the captives.

The Israeli military confirmed that a number of Israelis had been taken captive. A spokesman for Hamas' military wing, Abu Obeida, said the group was holding dozens of Israeli soldiers captive in “safe places” and tunnels in the Gaza Strip. If true, the claim could set the stage for complicated negotiations on a swap with Israel, which is holding thousands of Palestinians in its prisons.

The Hamas assault into southern Israel left a trail of civilians' bodies where they had encountered the advancing gunmen.

On the road outside the town of Sderot, a bloodied woman slumped dead in the seat of her car. Inside the town, bodies of at least six people gunned down at a bus shelter were laid out on stretchers on the street, their bags set nearby on the curb. Elsewhere, a woman knelt in the street and embraced a dead family member whose body was stretched out next to a pink motorcycle that lay on its side. The rider’s hand with a glove and a foot in a racing boot extended out from under the sheet.

In the kibbutz of Nahal Oz, just 4 kilometers (2.5 miles) from the Gaza Strip, terrified residents who were huddled indoors said they could hear constant gunfire echoing off the buildings as firefights continued.

“With rockets we somehow feel safer, knowing that we have the Iron Dome (missile defense system) and our safe rooms. But knowing that terrorists are walking around communities is a different kind of fear,” said Mirjam Reijnen, a 42-year-old volunteer firefighter and mother of three in Nahal Oz.

In a televised address, Israeli Defense Minister Yoav Gallant warned that Hamas had made “a grave mistake” and promised that “the state of Israel will win this war.”

Israel's military was bringing four divisions of troops as well as tanks to the Gaza border, joining 31 battalions already in the area, the spokesman Hagari said. A major question now was whether Israel will launch a ground assault into Gaza, a densely populated enclave of more than 2 million people, a move that in the past has brought intensified casualties.

Hamas said it had planned for a potentially long fight. “We are prepared for all options, including all-out war,” the deputy head of the Hamas political bureau, Saleh al-Arouri, told Al-Jazeera TV. “We are ready to do whatever is necessary for the dignity and freedom of our people.”

US President Joe Biden condemned “this appalling assault against Israel by Hamas terrorists from Gaza.” He spoke with Netanyahu and said Israel “has a right to defend itself and its people.” according to a White House statement.

Saudi Arabia, which has been in talks with the US about normalizing relations with Israel, released a statement calling on both sides to exercise restraint. The kingdom said it had repeatedly warned about “the dangers of the situation exploding as a result of the continued occupation (and) the Palestinian people being deprived of their legitimate rights.”

Lebanon’s Hezbollah militant group congratulated Hamas, praising the attack as a response to “Israeli crimes.” The group said its command in Lebanon was in contact with Hamas about the operation.

The attack comes at a time of historic division within Israel over Netanyahu’s proposal to overhaul the judiciary. Mass protests over the plan have sent hundreds of thousands of Israeli demonstrators into the streets and prompted hundreds of military reservists to avoid volunteer duty — turmoil that has raised fears over the military’s battlefield readiness and raised concerns about its deterrence over its enemies.

It also comes at a time of mounting tensions between Israel and the Palestinians, with the peace process effectively dead for years. Over the past year Israel’s far-right government has ramped up settlement construction in the occupied West Bank, Israeli settler violence has displaced hundreds of Palestinians there, and tensions have flared around a flashpoint Jerusalem holy site.

Israel has maintained a blockade over Gaza since Hamas seized control of the territory in 2007. The bitter enemies have fought four wars since then.