Even as Palestinian Authority President Mahmoud Abbas condemned the attack, Israeli Prime Minister Netanyahu said he was "glad" but insisted it "is not enough."
Addressing reporters Tuesday night, Prime Minister Benjamin Netanyahu called for national unity against "those human animals who committed this massacre" and against those -- singling out Hamas, the Islamic movement and the Palestinian Authority -- who he claims "disseminate libels against the state of Israel."
"There are those who wish to uproot us from the capital, from our land," he said, referring to Jerusalem. "They will not be successful... We have to unify forces."
Netanyahu spoke hours after the latest act of violence to afflict the region, this time at a synagogue in West Jerusalem's Har Nof area.
Photos taken inside the Jewish house of worship, and released by Israeli officials, painted a grim scene -- from lifeless bodies sprawled on a floor to a shattered pair of glasses to blood seemingly everywhere, drenching holy books, prayer shawls and walls.
Three dual U.S.-Israeli citizens and a British-Israeli citizen died in the attack before police shot and killed the two assailants.
The terror attack -- the deadliest in Jerusalem since a man with an automatic weapon killed eight seminary students in March 2008
-- came at a particularly tense time in that city and the region at large. It follows a series of recent deadly stabbings and vehicle incidents that, while not the large-scale suicide bombings that defined last decade's second intifada or the rocket attacks from Gaza earlier this year, have left Jerusalem on edge.
Netanyahu blasts 'incitement' by Palestinian leaders
The answer to what's next came quickly, as Israeli authorities moved into the slain attackers' East Jerusalem neighborhood of Jabel Mukaber to demolish their homes on Netanyahu's order. The Palestinians' official WAFA news agency reported 13 people were arrested, including an al-Aqsa Mosque guard.
Jerusalem Mayor Nir Barkat -- whose city is about two-thirds Jewish and one-third Arab -- said the attack were incited by Hamas and terror organizations who use "rumor and misfacts" about Palestinians are treated in the city.
Mark Regev, Netanyahu's spokesman, said that authorities were also beefing up security around Jerusalem.
"The goal is to make sure that there are not copycat attacks," Regev said.
The war of words between the two sides, meanwhile, continued.
"(Abbas) does not send out terrorists, he doesn't directly encourage acts of terror, and this is good," the Netanyahu said, echoing an assessment by an Israeli security chief. "On the other hand, the incitement of the Palestinian Authority -- and he heads the Palestinian Authority -- and even some things he says ... encourage terrorism, in terms of incitement (of) tensions that run high."
There was no such equivocation about Hamas, the Palestinian militant group that controls Gaza. It's been at odds with Israel and also with Abbas' Fatah movement, which controls the West Bank.
Hamas did not claim responsibility for the synagogue attack, though it didn't back away from it either. Sami Abu Zuhri, a spokesman for the group, instead linked the attack to the discovery Sunday of an Palestinian bus driver hanged in his bus
not far from where Tuesday's attack occurred. (For his part, Netanyahu said that claims the bus driver was killed were lies and that his death was ruled a suicide.)
Senior Hamas official Ghazi Hamad predicted to Al Jazeera International that "there will be more revolution in Jerusalem, and more uprising."
"Hamas in general supports action against the occupation," Hamad said. "Hamas supports any military action against the occupation anywhere it can be carried out."
Four rabbis killed
The latest example of such an action came at 7 a.m. Tuesday, when two Palestinian men entered a synagogue in an ultra-Orthodox neighborhood, where about 30 worshipers in prayer shawls and phylacteries were doing their morning prayers.
"They began attacking worshipers, stabbing them before opening fire," Israel's foreign ministry said.
The four killed were all rabbis: Avraham Shmuel Goldberg, 58; Aryeh Kupinsky, 43; Moshe Twersky, 59; and Kalman Levine, 55. Goldberg was a dual British-Israeli citizen, and the other three were U.S.-Israeli citizens -- which is why the FBI is investigating the attack, according to a U.S. law enforcement official.
"When four great men, wonderful men, wise in Torah study, are slaughtered while praying in public, there is no public grieving greater than that," said a rabbi who eulogized the men later Tuesday, before their burial.
Eight others were wounded, including three who were seriously hurt and a policeman who was critically wounded, according to the foreign ministry.
Officials overseas such as British Foreign Secretary Philip Hammond strongly condemned the killings, and U.S. Ambassador to Israel Dan Shapiro called them "a barbaric new low in the sad and outrageous history of such attacks."
"Tragically, this is not the first loss of life that we have seen in recent months," U.S. President Barack Obama said after condemning "in the strongest terms" attacks he said were "a tragedy" for Israel and the United States. "Too many Israelis have died, too many Palestinians have died. And at this difficult time, I think it's important for both Palestinians and Israelis to work together to lower tensions and reject violence."
While no group claimed responsibility for the attack, Israeli officials say the attackers came from East Jerusalem, where Palestinians can move more freely about the city than those living in Gaza, who must pass through stringent checkpoints.
Ma'an, a Palestinian news agency, identified the two men as Ghassan Abu Jamal and his cousin, Udayy.
Whether their actions were part of a coordinated campaign or a spontaneous reprisal, Tuesday's attack raises the specter of yet more violence against civilians.
The latest wave began earlier this year with the kidnapping of three Israeli teens, who were later found dead. Reprisal attacks, rocket fire and retaliatory airstrikes followed that incident, with more than 2,000 Palestinians and 67 Israelis reportedly killed after weeks of heavy fighting.
Much of the most recent unrest has been centered around Jerusalem. That includes the discovery of the body of Palestinian bus driver Yousuf al-Ramouni on Sunday, the same day an Israeli was stabbed with a screwdriver near central Jerusalem
Last week, a 20-year-old was stabbed
and killed in Tel Aviv, and three people were stabbed -- one fatally -- near the entrance to a settlement in the West Bank, the same spot where the three Israeli teens were kidnapped.