It was the first such attack on the city since the 2014 Gaza war between Hamas and Israel. There have been several smaller rounds of fighting since, reined in by Egyptian and UN mediations.
“This was basically a surprise,” military spokesman Brigadier-General Ronen Manelis told Israel Radio on Thursday.
“We don’t know who carried it out,” Manelis said, adding: “The Hamas organisation is the main organisation in the Strip. It is responsible for what happens within the Strip and what emanates from it.”
Hamas denied involvement in the rocket launches, which it said took place as its leaders met Egyptian delegates about efforts to secure a long-term ceasefire with Israel.
Islamic Jihad and the Popular Resistance Committees, two smaller Gaza armed factions, also denied responsibility.
Israeli analysts speculated that Palestinian militants opposed to any deal between Hamas and Israel were behind the launchings.
Naftali Bennett, a member of Netanyahu’s security Cabinet who is vying against him for rightist votes in the looming election, demanded the assassination of Hamas chiefs. “The time has come to defeat Hamas once and for all,” he said on Thursday.
Netanyahu also faced pressure from the centre-left opposition, whose leading candidate, former General Benny Gantz, said: “Only aggressive, harsh action will restore the deterrence that has eroded” under the prime minister’s watch.