Israel assassinated a senior commander of the Islamic Jihad group in the Gaza Strip on Tuesday, provoking a barrage of Palestinian rocket fire at Israeli communities as far north as Tel Aviv, in the most serious confrontation between the sides in months.

Islamic Jihad accused Israel of also targeting another of its top commanders in the Syrian capital, Damascus, Akram al-Ajouri. It mentioned nothing about his fate, but in a statement said his son was killed and warned that “Israel has crossed all the red lines.” The Israeli military had no comment on this attack.

The predawn missile strike on a building in Gaza City killed Bahaa Abu al-Ata, a mastermind of hundreds of attacks on Israeli soldiers and civilians who was planning another assault despite warnings from the Israeli military, army spokesman Lieutenant-Colonel Jonathan Conricus said on a call with reporters. The raid was ordered under Israel’s policy of stopping what it calls “ticking bombs,” Conricus said.

The violence has flared at a time of political turmoil in Israel, which is still struggling to form a government after two back-to-back elections. Prime Minister Benjamin Netanyahu approved the attack on Abu al-Ata, according to a statement from his office.

Israel’s shekel was the worst performer among Mideast currencies over the past day, depreciating 0.34% to trade at 3.5148 shekels per dollar at 9:21 Tel Aviv time, its weakest performance since October.

By mid-morning, Palestinian rocket squads had fired dozens of times at Israeli communities close to the border with Hamas-run Gaza and in Israel’s central heartland, the military said. Residents in those areas were instructed to stay close to bomb shelters, and schools and universities were closed for the day. Israel’s security cabinet convened to discuss the developments, and Israel Radio said Egypt was trying to mediate a cease-fire.

Bad Precedents

Israel hasn’t retaliated for the rocket fire with air raids, as it has done in previous rounds.

Assassinations, once a more frequent tool in Israel’s arsenal, have become relatively rare, and Conricus said Israel is not “going back to targeted military killings.” It has delivered messages to Palestinian militias that this operation was a one-time event, and the army is “not seeking to further escalate the situation.”

Even so, the military is preparing for “a number of days of fighting,” he said.

“This has all the hallmarks of being an extended event,” Conricus said.

(An earlier version of this story corrected a military spokesman’s comments.)