Four rabbis, three of them American, were slain during a prayer service Tuesday morning at a synagogue in Jerusalem.

Authorities say two Palestinian cousins, one armed with a meat cleaver, entered the synagogue during morning prayers and killed four rabbis. Three were American and the fourth British. A fifth victim, a police officer responding to the scene, died later.

One of the victims, Moshe Twersky, is a member of one of New York's most prominent Jewish families. His father, Isadore, was the founder of Harvard University's Center for Jewish Studies. His brother-in-law is the rabbi at the Riverdale Jewish Center in the Bronx.

The NYPD now has a security presence at the Riverdale Jewish Center to make sure things stay safe. A worker told News 12 the police presence also helps them "feel better." Temples throughout Westchester have also stepped up security in the wake of the attack.

The attack was the deadliest in Jerusalem since 2008. President Barack Obama condemned the attack and offered his sympathy to the families of the victims. Israeli Prime Minister Benjamin Netanyahu has promised retaliation and ordered the homes of the two attackers be demolished.