'This Week' Transcript: Hillary Clinton and Jeb Bush

— -- THIS IS A RUSH TRANSCRIPT FOR "THIS WEEK" ON DECEMBER 6, 2015 and it will be updated.

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ANNOUNCER: Starting right now, a special edition of THIS WEEK, act of terrorism in the homeland -- the brand new details about the killer couple who may have been inspired by ISIS, as stunning revelations emerge about the parents turned cold-blooded terrorists. The new indications she could have masterminded the massacre.

With the country shocked by the deadliest terror attack in America since 9/11, how do we keep the homeland safe?

This morning, Hillary and Jeb here live, taking on that critical question.

Plus, are tougher gun laws needed?

And is it time for boots on the ground to take on ISIS?

Clinton and Bush right now, exclusively on THIS WEEK from ABC News, a special edition of THIS WEEK WITH GEORGE STEPHANOPOULOS begins now.

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GEORGE STEPHANOPOULOS, ABC HOST: Good morning.

As we come on the air, ISIS has now claimed that the massacre in California this week, the deadliest terror attacks here since 9/11 was carried out by soldiers of its caliphate.

President Obama will speak to the nation from the Oval Office tonight.

With the latest on the investigation and what he'll do to defeat ISIS and keep America safe. And we have complete coverage here this morning -- exclusive interviews with Hillary Clinton and Jeb Bush.

Senior justice correspondent Pierre Thomas starts us off -- good morning, Pierre.

PIERRE THOMAS, ABC NEWS CORRESPONDENT: Good morning, George.

The FBI investigation involving hundreds of agents is at full tilt, as the law enforcement and intelligence community wrestles with a new, unpredictable phase, where a potentially deadly homegrown terror threat is growing.

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THOMAS (voice-over): The moment urgent j the president of the United States huddled with his top national security advisers in the wake of the San Bernardino massacre.

While the FBI and White House are not yet ready to officially say the attack was inspired by ISIS, that is a growing concern after we learned the female member of the killer couple swore allegiance to the leader of ISIS.

ISIS, meanwhile, seizing the moment, calling the killers supporters.

BARACK OBAMA, PRESIDENT OF THE UNITED STATES: ISIL and other terrorist groups are actively encouraging people around the world and in our country to commit terrible acts of violence.

THOMAS: This morning, the race is on to find out more about the plot. The FBI continues to try to exploit phones and computers left behind by the suspects, even though they took great efforts to try to destroy evidence.

Family, friends and associates being interviewed, with the investigation international, as the FBI focuses on trips abroad, including to Saudi Arabia and Pakistan.

UNIDENTIFIED MALE: So far, we have no indication that these killers are part of an organized larger group or form part of a cell.

THOMAS: But if this couple was truly inspired by ISIS, it marks a dangerous evolution in the U.S. terror threat. The FBI director has been warning for months about ISIS' unprecedented social media campaign, urging potentially thousands of followers here in the U.S. to attack.

UNIDENTIFIED MALE: It's as if a devil sits on someone's shoulder all day long saying kill, kill, kill.

THOMAS: An ISIS-inspired attack narrowly averted in May, when two men armed with assault rifles targeted a Texas cartoon conference about the Prophet Muhammad.