Two Palestinians attacked a Jerusalem synagogue killing worshippers praying inside with knives, axes and guns, according to Reuters.
Four people were killed in a shootout with police, in the deadliest attack in Jerusalem in years, Reuters reported.
The attack occurred at a religious seminary site on Harav Shimon Agassi Street, mostly populated bya largely Orthodox Jewish community in the Har Nof neighbourhood, BBC News reported.
Prime Minister Benjamin Netanyahu vowed that Israel will "respond harshly" to the attack, which he denounced as a "cruel murder of Jews who came to pray and were killed by despicable murderers," according to BBC.
"This is a direct result of incitement led by Hamas and Abu Mazen, incitement that the international community has been irresponsibly ignoring. We will respond with a heavy hand to the brutal murder of Jews who came to pray and were killed by lowly murderers," Netanyahu said, Reuters reported.
Israeli police described the assault as a terrorist attack and said the two Palestinian assailants were cousins from east Jerusalem, BBC reported. Hamas, the militant Palestinian group that runs the Gaza Strip, praised the attack but stopped short of claiming responsibility.
According to a police spokesperson, the attackers were Palestinians from east Jerusalem, which has been the scene of relentless clashes between Israeli police and Palestinian protesters in recent months, according to BBC.
Hamas spokesman Sami Abu Zuhri praised the attack and called for more bloodshed, BBC reported.
"Hamas calls for the continuation of revenge operations and stresses that the Israeli occupation bears responsibility for tension in Jerusalem," Hamas spokesman Sami Abu Zuhri said, according to Reuters.
