JERUSALEM >> Israeli forces today struck targets across the Gaza Strip, including the offices of Hamas’ supreme leader, in response to a surprise rocket attack from the Palestinian territory, as the military bolstered its troops and rocket-defense systems in anticipation of a new round of heavy fighting with the Islamic militant group.

Israel opened public bomb shelters in most major cities and civil defense authorities canceled sports events and public transportation in southern Israel. The Israeli army said air raid sirens wailed across southern Israel late tonight, and Israeli media reported at least 10 rockets fired into the country, but it provided no further details.

“Israel will not tolerate this. I will not tolerate this,” Prime Minister Benjamin Netanyahu declared during a White House meeting with President Donald Trump.

“Israel is responding forcefully to this wanton aggression,” he said. “We will do whatever we must do to defend our people and defend our state.”

Ahead of the Israeli airstrikes, Hamas’ leadership went into hiding.

Several airstrikes rocked Gaza, including an explosion that destroyed the office of Hamas leader Ismail Haniyeh. The Israeli military issued a statement confirming it bombed the building, which had “served as an office for many military meetings.” An earlier blast destroyed a multistory building in Gaza City that Israel said had served as a Hamas military intelligence headquarters.

There were no immediate reports of casualties. In both blasts, Israel fired warning shots to evacuate the buildings. But the airstrike on the multistory building was so powerful it sent debris flying onto the roof of The Associated Press bureau, located on the 11th floor of a nearby high-rise.

The sudden conflagration came at a time when both Netanyahu and his Hamas foes are in desperate situations.

Netanyahu is in a tight race for re-election, and just two weeks before the April 9 vote, faces tough criticism from challengers who accuse him of being too soft on Hamas.

In Washington to celebrate the U.S. recognition of Israel’s control of the Golan Heights, Netanyahu instead was forced to cut short his trip under heavy pressure to strike back at Hamas.

Earlier, Haniyeh issued a statement warning Israel against heavy retaliation. He said the Palestinian people “will not surrender” and its militant factions “will deter the enemy if it exceeds the red lines.”

In Beirut, the powerful Lebanese militant group Hezbollah said its leader, Hassan Nasrallah, met today with a Hamas delegation led by top official Saleh Arouri. Hezbollah said they discussed the Gaza situation and “Israeli aggression.”

Hamas is facing perhaps its toughest domestic test since seizing control of Gaza from the rival Palestinian Authority 12 years ago.

An Israel-Egyptian blockade, imposed to weaken Hamas, combined with sanctions by the Palestinian Authority and mismanagement by the Hamas government, have all fueled an economic crisis that has left Gaza with an unemployment rate above 50 percent.

Hamas has been leading weekly protests along the Israeli border for the past year in hopes of easing the blockade, but the demonstrations, in which some 190 people have been killed by Israeli fire, have done little to improve conditions.

Last week, hundreds of Gazans protested the dire conditions, a rare expression of public discontent against the authoritarian government. Hamas responded with a violent crackdown, beating and arresting dozens of demonstrators and drawing rare public criticism.

The rocket attack, which caught Israel off guard, may have been an attempt by Hamas to divert attention from its growing domestic woes.

Israel and Hamas have fought three wars, most recently in 2014. Although neither side appears to have an interest in a full-fledged war, fighting could easily spin out of control. The 2014 conflict lasted 50 days and ended with over 2,000 Palestinian deaths, including hundreds of civilians, and 73 killed on the Israeli side.

Netanyahu faces the difficult task of delivering a tough blow to Hamas while avoiding protracted fighting that could work against him on election day.

Yaakov Amidror, a former national security adviser to Netanyahu, said a mild response was not an option.

“It will be something on a bigger scale,” he said.

“He doesn’t want a war before elections, but they put him in a corner,” he added. “After three missiles reaching the heart of Israel, the chance of a big escalation including a ground offensive, is very high.”

Today’s attack came 10 days after rockets were fired from Gaza toward Israel’s densely populated commercial capital of Tel Aviv, and the Israeli military struck back. Gaza’s Hamas leaders said the rocket was fired accidentally and the fighting quickly subsided.

The sounds of air raid sirens jolted residents of the Sharon area, northeast of Tel Aviv, shortly after 5 a.m. today, sending them scurrying to bomb shelters. The sound of a strong explosion followed.

The rocket destroyed a residential home in the farming community of Mishmeret, wounding six members of a family. The Magen David Adom rescue service said it treated seven people, including two women who were moderately wounded. The others, including two children and an infant, had minor injuries.

The Israeli military said Hamas militants fired the rocket from southern Gaza. It said its Iron Dome rocket-defense system was not activated because the attack in central Israel had not been anticipated. The army added it was reinforcing its missile defense batteries in preparation for an escalation.

Maj. Mika Lifshitz, a military spokeswoman, said it was a self-manufactured rocket with a range of 120 kilometers (75 miles), making it one of the deepest rocket strikes ever carried out by Hamas.

Lifshitz added that two armor and infantry brigades were being mobilized to the Gaza front and that a limited drafting of reserves was also taking place.

The cities of Tel Aviv and Beersheba opened public bomb shelters. Civil defense officials canceled sporting matches and train service in southern Israel. Schools were ordered to hold classes in bomb shelters, and large public gatherings were banned.

The family home in Mishmeret was left in ruins, with tiles, broken furniture and debris scattered about. A shattered baby’s crib lay among the rubble and two family dogs died in the explosion.

“I nearly lost my family,” said Robert Wolf, grandfather of the injured residents. “If we hadn’t gotten to the bomb shelter in time, I would now be burying all my family.”

Netanyahu came under heavy criticism from allies and opponents for what they say has been an ineffective policy containing Gaza militants. He has conducted indirect cease-fire talks through Egyptian mediators in recent months, and even allowed the delivery of millions of dollars of Qatari aid to Hamas to ease harsh conditions in Gaza.

“The reality in which Hamas turned Israel into a hostage is unprecedented and unfathomable,” his chief challenger, Benny Gantz, wrote on Twitter today. Gantz is a former military chief who led the army during the last Gaza war in 2014.

Netanyahu also came under attack from his own nationalistic allies.

“Israel’s deterrence has collapsed, and it has to be said in all honesty Netanyahu has failed against Hamas,” said Education Minister Naftali Bennett, head of the Yamin HeHadash faction in Netanyahu’s coalition.

Witnesses reported seeing Hamas evacuating personnel from government premises. Hamas also announced that its Gaza chief, Yehiya Sinwar, had canceled a public speech. Other leaders turned off their mobile phones, while Hamas police were seen evacuating their stations. Hamas even released some prisoners it was holding, in another sign of anxiety.

Israel shut down its main crossings into Gaza and imposed restrictions on fishing off the Gaza coast.

Egypt, Qatar and the United Nations are trying to broker a long-term truce between Israel and Hamas.