Four days later, the Palestinians employ a new tactic, sending kites across the border, some carrying explosive devices, to set fire to farmland.
Further rounds of rockets were launched into Israel following the reprisal attacks.
The usual suspects - Hamas, the Popular Resistance Committees and the Iran-backed Palestinian Islamic Jihad - each denied their respective terror groups were behind the projectile attacks.
"We hold Hamas responsible for all attacks launched from the territory under its control, and urge the global community to publicly recognize that this offensive came unprovoked and that Israel has the full right to do whatever is required to safeguard the security of its residents and citizens", Singer said.
Just after dawn, six more missiles were fired from Gaza toward Israeli border towns but all but one were intercepted by Israel's Iron Dome defense system, the military said.
The fighting broke out as Egyptian mediators were in Gaza trying to broker an expanded cease-fire deal between the bitter enemies.
The blasts were so powerful that smoke could be seen in Gaza City, 25 kilometers away from some of the strikes.
Explosions could be heard throughout the night in Gaza and fireballs lit the sky.
The escalation on Thursday followed a day of unrest in Gaza, where Hamas, the militant group that controls the Palestinian enclave, had forcibly put down demonstrations against deteriorating living conditions. Smaller flare-ups have occurred sporadically since Israel and Hamas fought their last war, in 2014.
At the time, Netanyahu issued a warning to Hamas, rejecting suggestions that Israel would be reluctant to take tough action in Gaza ahead of national elections next month.
Prior to the airstrikes on Gaza late Thursday, Israeli Prime Minister Benjamin Netanyahu, who also serves as defense minister, held an emergency security consultation at army headquarters in Tel Aviv. An Israeli-Egyptian blockade, combined with sanctions by the rival Palestinian Authority and mismanagement by the Hamas government, have fueled an economic crisis in the territory.
On February 28, 2019, a United Nations probe says Israel may have committed "war crimes or crimes against humanity" in responding to unrest in Gaza, as snipers "intentionally" shot civilians, including children.
"In keeping with the public interest, the commission has chose to exceptionally postpone its activities scheduled for this day", the body which organizes the protests said in a statement. Hamas possesses a large arsenal of rockets and missiles capable of striking deep inside Israel.