JERUSALEM, Israel -- Within moments after arriving for the first day of the new school year Monday, children in Sderot heard the all-too-familiar Color Red air raid siren, signaling an incoming rocket attack from Gaza-based terrorists.

Moments later the rocket exploded in an open field and children resumed opening day activities.

On Sunday, three rockets fired about 9:00 a.m. damaged two factory buildings in the Sderot industrial area. Paramedics treated several residents for shock. One of the factories sustained a direct hit in June, which injured one of its employees. 

The third rocket landed in an open area, without damaging any property or injuring anyone. 

An Islamist group calling itself the Council of Jihad claimed responsibility for the attacks, Israel's Channel 2 reported.

"The jihad is the path of Allah against Jewish criminals," the group's statement read. "Jewish thieves must know that Muslims will dedicate their blood at every Muslim holy place."

Gaza-based Arabs have fired more than 10,000 rockets and mortar shells on Sderot and the surrounding area since 2001.

Over the past several years, terrorists have acquired longer-range and more accurate Grad-type rockets, which have reached Ashkelon, Ashdod and Beersheva.