New York police tightened security Monday at synagogues and other Jewish institutions following an attack hours earlier on the Otzar HaTorah Jewish day school in Toulouse, France.

Police spokesman Paul Browne said NYPD would increase patrols and tighten surveillance around more than 40 sites in response to the attack and other “events abroad.”  

Rabbi Jonathan Sandler, his two young sons ages 3 and 6, and the 8-year-old daughter of the school’s principal were shot to death by a gunman who arrived on a motorcycle. The gunman used two pistols in the attack and also left an unnamed 17-year-old boy critically injured before escaping the scene.

Two Paris synagogues have received threatening letters since Friday; one of the two was received on Monday morning. “You are the people of Satan, Hell is waiting for you,” was the message written in the letter, sources told the AFP news agency. Paris police have launched an investigation.

Meanwhile, Israeli Defense Minister Ehud Barak noted in testimony before the Knesset Foreign Affairs and Defense Committee on Monday that the Lebanon-based Hizbullah terrorist organization is likely to attack Jewish targets worldwide.

Iran patronizes, sponsors and generously funds the group, Barak pointed out, and itself is also dedicated to initiating terror attacks as well. 

In recent months a number of Iranian attempts on Israeli and Jewish targets have been foiled in several international venues, among them Thailand, India and Azerbaijan.