JERUSALEM — In a surprise strike before dawn on Tuesday, Israeli forces killed a senior commander of the Palestinian Islamic Jihad militant group in the Gaza Strip, officials said, in a rare targeted killing that was likely to prompt a fierce response.
Islamic Jihad said that the commander’s wife was also killed in the attack, which the Israeli military said was a missile strike from a fighter jet.
Right away, militants in Gaza began firing barrages of rockets toward southern Israel from the Palestinian coastal enclave. A spokesman for the Israeli military, Lt. Col. Jonathan Conricus, put the unofficial count of rockets fired from Gaza in the dozens so far, though with no damage yet reported. Alarm sirens began ringing in Tel Aviv and surrounding neighborhoods.
Islamic Jihad released a statement saying “our response to this crime will have no limits.” The group called the strike “a declaration of war against the Palestinian people.”
Bracing for a broader conflict, the Israeli military said in a statement that it had deployed troops and was “prepared for a wide range of offensive and defensive scenarios.”
At first light, the Israeli police announced that roads around the Gaza Strip had been closed to traffic and that the train service in southern Israel had been suspended. Schools on both sides of the border were closed.
The Israeli military confirmed the attack on the commander, Baha Abu al-Ata, describing him as a “ticking bomb” who was “responsible for most of the Palestinian Islamic Jihad’s activity in the Gaza Strip.” The group is listed as a terrorist organization by many countries, and is supported by Iran.
Confirming his death, Islamic Jihad described Mr. Abu al-Ata as one of the most prominent members of the movement’s military council and the group’s commander of the northern region of the Gaza Strip.
Hamas, the larger Islamic militant group that dominates in Gaza, said it mourned the commander’s death and said that the killing would not go unpunished.
The killing came after a period of relative quiet along the border, though there had been some sporadic rocket fire of late out of Gaza, a tiny Palestinian enclave along the Mediterranean coast.
The violence came at a time of political tension within Israel, with Prime Minister Benjamin Netanyahu fighting for his political future and leading a caretaker government after two elections, in April and September, ended inconclusively. Mr. Netanyahu has been serving as both prime minister and defense minister for the past year.
The office of Mr. Netanyahu said in a statement Tuesday that the attack had been carried out on the recommendation of the military chief of staff and the head of the Shin Bet internal security agency, and with the approval of Mr. Netanyahu and the Israeli cabinet.
The military said Mr. Abu al-Ata was responsible for rocket fire toward the Israeli border town of Sderot in August and early November and was preparing further attacks.
Militant groups in Gaza have clashed with Israel several times in recent years, with the last deadly conflagration taking place over several days in May. A devastating war in the summer of 2014 lasted 50 days and ended with a fragile cease-fire that has since been broken many times.
Targeted strikes against militant leaders have led to war before. In 2012, an Israeli airstrike that killed Ahmed al-Jabari, the Hamas military commander at the time, became the opening shot of an eight-day war.
Islamic Jihad and Hamas are uneasy rivals in Gaza. But in times of hostility with Israel, the groups tend to make common cause.
In the hours after the attack masked militants of Islamic Jihad surrounded the two-story building where Mr. Abu al-Ata and his wife were killed. It is in Shejaiya, a neighborhood east of Gaza City that saw fierce battles during the 2014 war.
Mutassem Hilis, 23, a university student and a neighbor of the Abu al-Ata family in Shejaiya, said he was woken up by the blast. Mr. Hilis said he came out of his building and saw Mr. Abu al-Ata’s body on the sidewalk. One of Mr. Abu al-Ata’s young sons lay injured on the ground, and was later driven off to hospital, he said. The body of Mr. Abu al-Ata’s wife was found in a school opposite the family house.
Days ago, Mr. Netanyahu appointed Naftali Bennett, an often provocative right-wing politician and former education minister who has long urged a more aggressive approach to Gaza, to the defense ministry post in a political move that analysts said was designed to shore up Mr. Netanyahu’s right-wing bloc of allied parties. But it is unlikely that Mr. Bennett played any leading role in planning or approving the Tuesday action.
Mr. Netanyahu’s chief political rival, Benny Gantz, a former military chief of staff and leader of the centrist Blue and White party, is trying to form a new governing coalition. On Tuesday, Mr. Gantz expressed support for the military action against Palestinian Islamic Jihad, writing on Twitter that the political echelon and the military had “taken a correct decision tonight for the security of Israel’s citizens and the residents of the south.”
Isabel Kershner reported from Jerusalem, and Iyad Abuheweila from Gaza. Ibrahim El-Mughraby contributed reporting from Gaza.