Sirens rang in southern Israeli cities and towns throughout Tuesday as a continuous barrage of mortars and rockets was launched from the Gaza Strip — followed by an announcement by Palestinian militants that they had agreed to a cease-fire.
The assault was believed to be the biggest of its kind in four years.
Israeli police said that militants from the Islamic Jihad group fired 130 projectiles, apparently in retaliation for Israel's killing of three guerrillas on Sunday. The Israeli military gave a lower figure of 70.
The three guerrillas were killed after a bomb was planted on the border fence between Gaza and Israel, the site of weeks of Palestinian protest.
Seven Israelis, including three soldiers, were wounded and required hospitalization after being hit by shrapnel from missiles intercepted by the Iron Dome defense system.
The Israeli army said it had struck back against more than 30 Gaza military targets belonging both to the ruling Hamas militant group and to Islamic Jihad, including "a terror tunnel penetrating half a mile into Israel via Egypt."
According to Israeli police, the Iron Dome intercepted about half of the projectiles, which had been launched from Khan Younis, a city in southern Gaza, toward cities in the Negev desert. Other missiles failed to detonate or landed in unpopulated areas.
Late Tuesday night, a spokesman for Islamic Jihad, Daoud Shehab, appeared on Al Jazeera television and said the group had agreed to an Egyptian-brokered cease-fire beginning at midnight. "We are committed as long as Israel is committed to it," he said.
However, there was no confirmation from Egypt and no immediate response from Israel.
Earlier, Israeli residents living in border communities had been instructed to remain within a 10-second range of air raid shelters. One rocket landed next to a kindergarten in the early morning, and shrapnel damaged several cars in the city of Sderot later in the day.
An Israeli army spokesman, Lt. Col. Jonathan Conricus, said the escalation marked the "largest amount of rockets and mortars fired at Israel since 2014," when a summer war between Israel and Hamas, the Islamist group ruling Gaza, cost the lives of over 2,000 Palestinians and 70 Israelis, most of them soldiers.
Late Tuesday, in a rare joint statement, Hamas and Islamic Jihad together accepted responsibility for the daylong salvo against Israel. "The gunfire is a response to Israeli aggression and crimes against the Palestinian people," they said.
The Israeli army spokesman, Brig. Gen. Ronen Manelis, described the day as "a different form of terror attack against Israel that we have no intention to permit" following what he described as the failure of Hamas to penetrate Israel, harm Israelis or bring any benefit to its own population during two months of demonstrations. He blamed Iran for its financial support of Islamic Jihad.
Since March, thousands of Gazans have gathered at the border weekly to protest a growing humanitarian crisis in what they often describe as the world's largest open-air prison. The Gaza Strip, an overcrowded coastal enclave, has been held under an Israeli and Egyptian blockade since Hamas took control of the area from the Palestinian Authority more than a decade ago.
About 115 Gazans have died in clashes with the Israeli army since the protests began, and Israel has faced international condemnation for its use of sharpshooters.
Tuesday, however, marked the first time rockets or missiles have been aimed at Israel since the start of the confrontations.
As a new wave of air raid sirens sounded along the 32-mile border well into the night, the rumble of air force jets provided a constant background noise to Israelis living in Tel Aviv and Jerusalem. Manelis said that Israel did not intend to escalate but that continued rocket and mortar attacks "will only draw a more forceful response."
Manelis said the long fusillade proved that "Hamas is losing control of Gaza," and said that "terror of any type will be met with great force."
Israeli Defense Minister Avigdor Lieberman said that "every location terror organizations use to launch missiles is a legitimate target for air force strikes."
For the last two months, Hamas has maintained that the massive weekly protests are nonviolent. The Israeli army has released images of protesters using weapons ranging from slingshots to submachine guns, and numerous attempts to breach the Israeli border with knives or bombs, to prove the contrary.
Israeli Prime Minister Benjamin Netanyahu, who called for an urgent meeting of his top security team for Tuesday evening, posted a fiery red poster emblazoned with a message in capital letters on his official Twitter account.
Shehab, the Islamic Jihad spokesman, said the rockets constituted "a blessed response from our resistance."
"We will continue to defend our people everywhere," he said in an interview. "The resistance has the right to respond to the crimes of the occupation."
No Gazans were reported wounded Tuesday.
In a preplanned action, a fleet of more than 30 small boats carrying two students and several medical patients set sail from Gaza in an attempt to symbolically break through the sea blockade.
Gazan hospitals have reported they are at a breaking point following two months in which their systems have been overwhelmed with thousands of injuries. The Israeli navy detained and boarded a boat about 5.5 miles into Mediterranean waters, towing it to the Israeli port of Ashdod.
The Israeli army said, in a statement, that "the Hamas terror organization, who is behind this attempt to breach the naval blockade, is trying to carry out a propaganda operation whilst cynically using its people for that purpose."
Adham Abu Salmiya, a spokesman for the flotilla organizers, announced the launch of "a second freedom boat soon."
Matthias Schmale, the Gaza director for the principal United Nations organization charged with supporting Palestinian refugees in Gaza, lamented the "very worrying continuous firing of rockets back & forth between Israel and #Gaza all day." That drew a withering response from Emmanuel Nahshon, the spokesman for Israel's Foreign Ministry, who said "the gold medal for blind hypocrisy" went to an agency "not willing, or afraid, to admit the difference between the aggressor (Hamas and its consorts) and the country protecting its citizens against aggression."
Special correspondents Tarnopolsky and Salah reported from Jerusalem and Gaza City, respectively.
2 p.m.: This article was updated with reports of a cease-fire and a change in the number of boats in the flotilla.
12:15 p.m.: This article was updated with staff reporting, a higher casualty toll, background information and comments.