Overnight between Monday and Tuesday, a rocket directly hit a building in Israel's southern city of Ashkelon, killing a man in his 40s, and seriously wounding two women.
The killed man was identified by the police as a Palestinian resident from the West Bank city of Hebron.
An Israeli military spokesperson said at least 370 rockets were fired at different communities in southern Israel over the past 24 hours, most of which were intercepted by the Iron Dome anti-rocket system.
The national rescue service said at least 75 people, mostly suffering light injuries or just panic, were treated during the period.
Schools in the south were cancelled for the second consecutive day under instruction from the military's Home Front Command.
Meanwhile in Gaza, Israeli warplanes carried out massive airstrikes, killing four, according to the Palestinian health ministry in the enclave.
The Israeli military issued a statement saying it struck some 150 targets over the past 24 hours.
According to a statement by the Israeli military, some 150 targets were struck over the past 24 hours, most of which were military targets belonging to the Hamas, an armed movement that runs Gaza, or the Palestinian Islamic Jihad, another Gaza-based Islamist group, and government structures used for military purposes.
Hamas has said the rocket attacks are "just the beginning" if Israel continues its "aggression," referring to Israel's airstrikes throughout the Palestinian enclave.
Meanwhile, Israel's security cabinet met in the military headquarters in Tel Aviv to discuss the next moves.
United Nations Secretary-General Antonio Guterres urged Israelis and Palestinians "to exercise maximum restraint," according to a statement.
Nickolay Mladenov, the UN special envoy to the Middle East, said the UN is working closely with Egypt in an effort to "ensure that Gaza steps back from the brink."
The recent escalation is "extremely dangerous and reckless. Rockets must stop, restraint must be shown by all! No effort must be spared to reverse the spiral of violence," he wrote on his Twitter account.
The abrupt flare-up was sparked by a failed Israeli undercover raid in Gaza on Sunday night.
The undercover soldiers, reportedly on a reconnaissance mission, were discovered by Hamas fighters, prompting a fire exchange that cost the lives of seven Palestinian militants, including a Hamas commander, and an Israeli military officer.
The sudden burst of violence potentially shattered hopes for a long-term agreement between Israel and Hamas, as Egyptian and the UN officials have been working to broker a cease-fire deal in exchange for Israeli easing its 12-year crippling blockade on Gaza.