Hackers have targeted about 19,000 French websites since a rampage by Islamic extremists left 20 dead last week, France's cyberdefense official said Thursday, NBC News reported. Calling it an unprecedented surge, Adm. Arnaud Coustilliere said some of the attacks were carried out by well-known Islamic hacker groups. The attacks, mostly relatively minor denial-of-service attacks, hit sites as varied as military regiments to pizza shops but none appeared to have caused serious damage, he said. France is on edge since last week's attacks, which began Jan. 7 at the offices of the satirical newspaper Charlie Hebdo. The paper, repeatedly threatened for its caricatures of the Muslim Prophet Muhammad, was burying several of its slain staff members Thursday.