Israel announced on Sunday that it struck over a dozen Hamas targets in the Gaza Strip in response to attacks by the Palestinian group. In a first wave of air strikes, Israeli "fighter jets targeted 10 terror sites in three military compounds belonging to the Hamas terror organization in the Gaza Strip," the army said in a statement early Sunday. "Among the targets were two Hamas munition manufacturing and storage sites and a military compound," the army said. The latest escalation came hours after thousands of Palestinians attended the funeral of a young female volunteer medic killed by Israeli fire in violence on the border in southern Gaza. The strikes were retaliation to rockets fired at Israel, as well as "various terror activities approved and orchestrated by the Hamas terror organization over the weekend," the army said. There were no immediate reports of casualties in Gaza. On Saturday evening, fighters in the Palestinian enclave fired two projectiles at southern Israel, where air raid sirens sent residents to bomb shelters. The Iron Dome aerial defense system intercepted one of the projectiles, while the other was believed to have fallen short of its target and hit within Gaza, according to the army. Early Sunday, four more projectiles were separately launched at Israel. Three were intercepted, the army said, with the fourth apparently hitting an open field. No group in Gaza claimed responsibility for the projectile attacks, which came shortly after the Saturday funeral of Razan al-Najjar, 21, a volunteer with the Gaza health ministry, who was fatally shot in the chest near Khan Yunis on Friday. Ambulances and medical crews attended the funeral, with Najjars father holding the white blood-stained medics jacket she wore when she was shot, as mourners called for revenge. Gazans have since March 30 staged border protests demanding the return of Palestinians to land they fled or were expelled from during the 1948 war surrounding Israels creation, now inside the Jewish state. The demonstrations have been accompanied by smaller clashes as youths hurl stones at Israeli soldiers and attempt to breach the border fence, at times laying explosive devices on the fence or throwing grenades. The weekend launches were the first since Israel struck scores of sites in Gaza earlier this week in retaliation for a barrage of rockets and missiles fired from the territory. Addressing Najjars death, the UN envoy for the Middle East, Nickolay Mladenov, said in a Saturday tweet that "Medical workers are #NotATarget!" and that "Israel needs to calibrate its use of force and Hamas need to prevent incidents at the fence." The Palestinian Medical Relief Society said Najjar was shot "as she was attempting to provide first aid to an injured protester", with three other first responders also hit by live fire on Friday. "Shooting at medical personnel is a war crime under the Geneva conventions," the PMRC said in a statement, demanding "an immediate international response to Israeli humanitarian law violations in Gaza". Najjars death brings the toll of Gazans killed by Israeli fire since the end of March to 123.