cnn.com – Your video will begin momentarily. Editor’s note: Are you there? Share images, if you can safely Jerusalem (CNN) — Jerusalem ramped up security after two Palestinian cousins wielding a gun and butcher knives attacked a synagogue during morning prayers, killing four worshipers and a policeman. Israeli Prime Minister Benjamin Netanyahu vowed a strong reaction to Tuesday’s killings. He characterized the attack, which drew condemnation from around the world, as the result of a “blood libel” fanned by Palestinian leaders.