JERUSALEM (AP) — The Israel military said early Monday that it struck Palestinian militants targets in Gaza and Syria in response to rockets fired toward southern Israel on Sunday evening, hours after Israel said it killed a Palestinian militant who tried to place a bomb along the Israel-Gaza barrier fence.

The Palestinian Islamic Jihad militant group claimed responsibility for the rocket barrages. Palestinians were furious over the image of the man’s lifeless body dangling off the front of an Israeli bulldozer that crossed into Gaza to retrieve it. There was also criticism in Gaza of the territory’s Hamas rulers for not responding.

The Israeli military reported air raid sirens throughout southern Israel and said at least 20 rockets had been fired. There were no reports of damage or injuries on the Israeli side, but it was the heaviest barrage of rockets from the Gaza Strip in several months. Air raid sirens continued into the evening, and Israel’s Home Front Command ordered the suspension of classes in Israeli schools in southern Israeli communities near the Gaza Strip on Monday and prohibited large gatherings.

In response to the rocket fire, the Israeli military said aircraft struck “dozens of Islamic Jihad terror targets throughout the Gaza Strip” and a facility belonging to the militant group outside Damascus.

The Gaza health ministry reported that four Palestinians were treated at the Al-Shifa hospital in Gaza City for wounds caused by the Israeli strikes.

Islamic Jihad said in a statement that the airstrikes on Damascus killed two of its members, identifying them as Salim Salim, 24, and Ziad Mansour, 23. It did not disclose their nationalities or elaborate on their roles. It vowed to respond to the deaths of its members.

Israel and the Islamic Jihad group engaged in a heavy round of fighting last November after the Israeli military killed a top Islamic Jihad commander.

Since then, Israel and Gaza’s more powerful Hamas group have been working through Egyptian mediators to cement an informal cease-fire. But Islamic Jihad has continued to try to carry out attacks.

Islamic Jihad said the man killed along the border was a militant. Israel said the man was planting explosives along the border fence. Amateur video on Palestinian social media showed an Israeli bulldozer crossing into Gaza and then lifting up his body.

Fawzi Barhoum, a Hamas spokesman, accused the Israeli military of abusing the dead body, saying that it “bears the consequences of the ugly crime.”

The military said it was removing the body in a way that prevented further danger to those around.

But the images generated widespread anger in Gaza, where it was seen as a provocation and violation of Islamic principles that call for respect for the dead.

It also sparked criticism of Hamas on social media, with people accusing the group of appearing weak and allowing Israel to operate with impunity inside Gaza’s territory. One image on social media showed a picture of Jesus draped with a Palestinian flag hanging off the front of a bulldozer.

Israeli Defense Minister Naftali Bennett rejected the criticism, noting that Hamas has been holding the bodies of two Israeli soldiers since they were killed in the 2014 Gaza war.

“I back the military, which killed the terrorists and collected the body,” he said. “That’s what should be done and that is what was done.”

The incident comes amid a relative lull along the security fence separating Israel from Gaza. Last week, Israel announced it would provide hundreds of additional work permits for Palestinians in the Gaza Strip, in a new step aimed at solidifying an informal cease-fire with the Hamas.

Tens of thousands of Gazans used to work in Israel. But Israel virtually sealed the border when it joined Egypt in imposing a crippling blockade on Gaza after Hamas seized power in the strip from rival Palestinian forces in 2007. The blockade, along with three wars between Hamas and Israel, has devastated the economy in Gaza, where unemployment is over 50%.