Palestinians reported that four people were killed, including several children, and several others were injured when IDF shells hit a house east of Gaza City on Tuesday afternoon.Palestinian medics said the dead youths were aged 12, 16 and 17. The 58-year-old owner of the house was also killed.RELATED:Hamas repeats commitment to keep unofficial truceIsrael vows to avenge Gaza mortar barragePalestinian rocket slams into AshkelonAnalysis: Gaza escalation shows IDF deterrence erodingThe IDF spokesperson said that following the launch of Kassam rockets, that the IDF fired mortar shells at the Kassam launch site. Apparently, innocent civilians were hit in the strike. The spokesperson stressed, however, that Hamas was responsible for firing Kassams from within densely populated civilian areas.A short time earlier, four Kassam rockets exploded in open fields in the Sha'ar Hanegev Regional Council. No injuries or property damage was reported.France said on Tuesday it was concerned about an escalation in violence in the Gaza Strip this week and called on both sides to show restraint."We are worried by the mounting rocket fire on Israeli territory -- which we have condemned -- and by the Israeli army's operations in the Gaza strip," French Foreign Ministry spokeswoman Christine Fages told a press briefing. "We have called on both sides to show the greatest restraint in order to avoid any escalation in violence which recent history has show can have disastrous consequences," she said.Hamas said in a statement that it would respond strongly to Israel's actions."The escalation will not pass unanswered. Escalation will be met with escalation and calm will be met with calm," it said. Following that statement, yet another Kassam rocket was fired at the coastal city of Ashkelon. The rocket, launched from the northern Gaza Strip, landed in open fields outside the on Tuesday evening. Earlier in the day, the IDF successfully thwarted an attack on soldiers in the northern Gaza strip on Tuesday, the IDF spokesperson said.An IDF force identified a group of terrorists preparing to fire an anti-tank missile at them and fired on the men, successfully striking their target.Palestinian sources said that two people were injured in that attack. The IDF operation followed yet another launch of Kassam rockets into Israel early on Tuesday morning, falling in open fields in the Eshkol Regional Council area. No one was injured in the attack.The IDF Spokesman Unit overnight Monday confirmed that IAF aircraft attacked two terror tunnels, two sites used for the manufacturing and storage of weapons and two further terrorist targets in the Gaza Strip."Direct targets were identified and all planes returned safely to their base," a statement by the IDF read. "The attack was in response to recently conducted attacks on southern communities," the statement continued. "The IDF will not tolerate the continued attack of settlements close to Gaza," the IDF statement said.Hamas medical officials said 19 people were wounded in the Israeli air strikes, including four terrorists, seven children and two women.Yaakov Katz contributed to this report.