JERUSALEM — More than 130 rockets have been fired at Israel from Gaza since an Israeli airstrike killed the leader of a Palestinian terrorist group.

Four Israeli civilians have been injured in the attacks, one severely, according to the Israel Defense Forces.

The IDF announced Saturday evening that the Iron Dome missile defense system intercepted 28 long-range Grad rockets targeting major Israeli cities including Beer Sheba, Ashdod and Ashkelon, out of 31 interception attempts.

The attacks began Friday night after Israel Air Force airplanes targeted and killed Zuhir Mussah Ahmed Kaisi, the secretary general of the Popular Resistance Committees, and another member of the group. The terrorists were responsible for planning a combined terror attack that was to take place via Sinai in the coming days, according to the IDF.

Also on Friday night, the IDF said it struck eight squads preparing to fire rockets at Israel from separate locations in northern and central Gaza as well as what it called two weapons manufacturing facilities in northern Gaza and a weapons manufacturing site in central Gaza, as well as what it called a terror activity site in southern Gaza.

At least 15 Palestinians reportedly have been killed in the airstrikes.

During a meeting Saturday evening with the mayors of the southern Israeli communities under attack, Prime Minister Benjamin Netanyahu praised the residents for their resilience in the face of the rocket barrage.

“We will continue to hit whoever plans to attack citizens of the State of Israel.  At the same time, we will continue to improve home front defense including by means of additional Iron Dome systems, the effectiveness of which was shown again over the weekend,” Netanyahu said.

The United States is “deeply concerned by the renewed violence in southern Israel,” U.S. State Department spokesman Victoria Nuland said in a statement. “We condemn in the strongest terms the rocket fire from Gaza by terrorists into southern Israel in recent days, which has dramatically and dangerously escalated in the past day.  We call on those responsible to take immediate action to stop these cowardly acts.”

“We regret the loss of life and injuries, and we call on both sides to make every effort to restore calm,” the statement concluded.

The PRC promised revenge for Kaisi’s assassination. “All options are open before the fighters to respond to this despicable crime. The assassination of our chief will not end our resistance,” Abu Attiya, a PRC spokesman said.

“Israel’s escalation creates a negative atmosphere and increases the tension, which leads to the increase in violence in the region,” Palestinian Authority spokesman Nabil Abu Rudaina said, according to CNN.

“We hold Hamas responsible for the recent incidents since the terror organization currently has jurisdiction in the area (Gaza). We will continue responding to any attack against Israel,” the IDF Spokesperson said in a statement. “The Hamas movement, although not the one performing the launchings, is not doing anything to prevent it either – We hold them responsible and will continue defending and attack as necessary.”

It is estimated that the long-range and mid-range rockets are being launched by Islamic Jihad terrorists, while the short-range rockets are being launched by the Popular Resistance Committee, according to the IDF. 

The IDF Home Front Command ordered schools closed Sunday in all cities and towns located from 4 miles to 25 miles from the Gaza border, affecting about 200,000 children.