The projectiles triggered warning sirens, and exploded in open areas in the Sdot Negev region, failing to cause injuries or damages.The attack came after a rocket launched from the Gaza Strip struck a factory in the industrial district of Israel's southern city of Sderot. The structure broke into flames following the strike.A group of employees manged to escape the blaze.Three people were lightly injured in the incident. Magen David Adom paramedics treated the three before transferring them to Barzilai Medical Center in Ashkelon. Palestinian officials in Gaza said shortly after the rocket attack, Israeli tanks had fired back into the northern part of the coastal strip, causing no injuries.An IDF spokeswoman said she was checking whether tanks had returned fire into Gaza.(Video: Tazpit News Agency) Emergency and rescue crews arrived to the site. At least ten firefighting teams were trying to control the flames and prevent the blaze from spreading to other buildings in the area. Police spokesman Micky Rosenfeld said the situation was "under control."Another rocket fired in the salvo landed in the Nativ Ha'asarah area north of the Strip but caused no damage or injuries. The Code Red rocket siren was sounded in two communities in southern Israel ahead of the attack.Alerts went off in the Hof Asheklon Regional Council and the Sha'ar Henegev Regional Council. The attack came after the Israel Air Force struck four targets in Gaza on Saturday morning in response to Palestinian rocket fire from the Hamas-run enclave on Friday. Targets included a weapons manufacturing site in central Gaza, and a weapons depot in south Gaza, the IDF said.The strikes came after the Iron Dome anti-rocket battery intercepted two incoming Gazan projectiles over the Ashkelon region.Prior to the interceptions, four Gazan rockets exploded in open areas in the Eshkol region, failing to cause injuries or damages. A fifth landed in the Hof Ashkelon area.Reuters contributed to this report.