USA Today:

Police spokeswoman Luba Samri said eight people were wounded in the assault, including police officers. Samri said the attackers were Palestinians from east Jerusalem.

One of the victims was Rabbi Moshe Twersky, 59, a native of Massachusetts, according to Haaretz. Aryeh Kupinsky and Kalman Zeev Levine, 43 and 55, respectively, were also U.S.-born. Avraham Shmuel Goldberg, 68, was born in the United Kingdom.

The attack took place in the Jewish neighborhood of Har Nof in the western part of the city. The attackers were shot and killed by police following a shootout. Police were searching the area for other suspects.

The Abu Ali Mustafa Brigades, the military wing of the Popular Front for the Liberation of Palestine, claimed responsibility for the attack, according to the BBC.

Yosef Posternak, who was at the synagogue at the time of the attack, told Israel Radio that about 25 worshipers were inside when the attackers entered.

"I saw people lying on the floor, blood everywhere. People were trying to fight with (the attackers) but they didn't have much of a chance," he said.

Israeli Prime Minister Benjamin Netanyahu said Israel will "respond harshly" to the attack. He said the international community "irresponsibly ignores" Arab attacks on Jews around the world and said "the cruel murder of Jews who came to pray and were caught by dark, murderous hands" would not go unpunished. Netanyahu called an emergency meeting of his Security Cabinet.

Palestinian President Mahmoud Abbas condemned the attack, the first time he has done so since a recent spike in deadly violence against Israelis began. He also called for an end to Israeli "provocations" surrounding the sacred site known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary. Abbas said it was wrong for either side to kill civilians.

Sami Abu Zuhri, a spokesman for Hamas, wrote in a post on Facebook that the incident in Jerusalem was a reaction to Israeli "crimes" and called for further attacks and bloodshed to take place.