JUDY WOODRUFF: It's deadliest attack in Jerusalem since 2008. Four people were brutally murdered at a synagogue today, before their Palestinian attackers were shot dead. Later, an Israeli police officer died of his wounds. The attack built on growing violence in the region.

Israeli soldiers and police swarmed to the synagogue in West Jerusalem moments after two Palestinian men burst into morning prayers, shooting and hacking their victims with meat cleavers.

Witnesses told of terror and blood.

MAN (through interpreter): It was horrific. I can't imagine such attacks would occur to our community.

JUDY WOODRUFF: Three of the dead were Americans with dual Israeli citizenship, including a rabbi from a renowned Hasidic family.

From Washington, President Obama condemned the killings.

PRESIDENT BARACK OBAMA: This is a tragedy for both nations, Israel, as well as the United States. And our hearts go out to the families who obviously are undergoing enormous grief right now.

JUDY WOODRUFF: Within hours, thousands of Israelis gathered for the victims' funerals.

In East Jerusalem, clashes erupted, as Israeli police fired tear gas and arrested relatives of the attackers. They turned out to be cousins, and members of the Popular Front for the Liberation of Palestine.

Israeli Prime Minister Benjamin Netanyahu ordered their homes demolished, as he vowed to respond with a heavy hand

BENJAMIN NETANYAHU, Prime Minister, Israel (through interpreter): As a nation, we will settle the score with every terrorist and their dispatchers. There are some who want to uproot us from our state and capital. They will not succeed. We are in a battle over Jerusalem, our eternal capital.

JUDY WOODRUFF: Netanyahu blamed Palestinian President Mahmoud Abbas for inciting the violence.

And, in London, Secretary of State John Kerry also had stern words for the Palestinians.

JOHN KERRY, Secretary of State: They must begin to take serious steps to restrain any kind of incitement that comes from their language, from other people's language.

JUDY WOODRUFF: But Palestinian radio described the attackers as martyrs. And, in Gaza, loudspeakers at mosques called out congratulations.

President Abbas criticized today's violence, but he put some of the blame on Israeli actions.

PRESIDENT MAHMOUD ABBAS, Palestinian National Authority (through interpreter): While we condemn this action, we also condemn the Israeli aggression on the holy sites, like burning mosques and churches. All of these actions are not helping the Palestinian and Israeli interests to establish a Palestinian state and live side by side in peace.

JUDY WOODRUFF: The militant group Hamas called the attack a natural reaction to the death of a Palestinian bus driver found hanged in his bus on Monday. Many Palestinians charged he was killed by Jewish assailants. Israeli police ruled it a suicide.

Tensions have been rising for weeks, with a series of other attacks on Israelis. They have been fueled by a renewed dispute over Jerusalem's holiest site, known to Muslims as the Noble Sanctuary and to Jews as the Temple Mount.

All of this follows last summer's Israel-Hamas war in Gaza, and it's raised Israeli concerns that a new Palestinian uprising, or intifada, may be coming.