Four Israelis have been killed and eight injured as two men armed with a pistol and meat cleavers attacked a West Jerusalem synagogue.
The attackers - Palestinians from East Jerusalem - were shot dead.
Israel's Prime Minister, Benjamin Netanyahu, vowed a "heavy" response and has already ordered the destruction of the homes of the attackers, the BBC reported.
It was the deadliest attack in six years in Jerusalem, which had seen weeks of unrest, partly fuelled by tension over a disputed holy site.
Three of the victims were dual Israeli-US nationals, the US state department has confirmed, while the fourth was a dual Israeli-UK citizen.
The funerals of all four men were held in Jerusalem, with thousands in attendance.
Mr Netanyahu blamed the attack on "incitement" by the militant group Hamas and Palestinian President Mahmoud Abbas.
Mr Abbas's office issued a statement saying: "The presidency condemns the attack on Jewish worshippers in their place of prayer and condemns the killing of civilians no matter who is doing it."
US President Barack Obama also condemned the attack, saying: "There is and can be no justification for such attacks against innocent civilians."
The Abu Ali Mustafa Brigades, the military wing of the Popular Front for the Liberation of Palestine, said it carried out the attack.