2nd LD-Writethru: Obama to address nation on steps to fight terrorism in wake of shooting rampage

U.S. President Barack Obama is to address the nation Sunday night on steps to fight terrorism in the wake of the recent shooting massacre in southern California, the White House said Saturday.

Obama will provide an update on the ongoing investigation into the Wednesday tragic attack in San Bernardino, California, in which two shooters killed 14 people and wounded 21 others, the White House said in a statement.

It said the steps being taken by the U.S. government after the attack were aimed at fulfilling Obama's highest priority: keeping American people safe.

"The President will also discuss the broader threat of terrorism, including the nature of the threat, how it has evolved, and how we will defeat it," the statement said.

Obama will reiterate his firm conviction that the Islamic State (IS) will be destroyed and that "the U.S. must draw upon our values -- our unwavering commitment to justice, equality and freedom -- to prevail over terrorist groups that use violence to advance a destructive ideology," it added.

Earlier Saturday, Obama was briefed on information which pointed to radicalization of the two shooters in the attack, the White House said.

"The President's team highlighted several pieces of information that point to the perpetrators being radicalized to violence to commit these heinous attacks," said the White House in a statement after Obama's meeting with leaders of U.S. law enforcement and intelligence community.

The team affirmed that they had no indication that the killers were part of an organized group or formed part of a broader terrorist cell, the statement added.

The U.S. Federal Bureau of Investigation announced on Friday it was now investigating the case as "an act of terrorism."

The FBI said so far the probe showed the couple may have been self-radicalized and there was no sign that they belonged to a terror group.

The two suspects, 28-year-old U.S. citizen Syed Farook and his 27-year-old wife Tashfeen Malik, had 1,600 rifle and handgun rounds of ammunition when they were killed in a shootout with police, and 2,000 nine-millimeter rounds and 2,500 .223 rifle rounds at home, as well as 12 pipe bombs and tools to make bombs, according to police.

And those do not include the hundreds of rounds they fired in the shooting attack and exchange of gunfire with police.

The extremist group IS said Saturday the couple were its followers and prayed to God to "accept them as martyrs."

It was revealed earlier that the wife had pledged allegiance to the IS on social media.

The Los Angeles Times reported Friday, citing an anonymous federal law enforcement official that Farook had contact with at least two militant organizations overseas, including the al-Nusra Front, an al-Qaeda affiliate in Syria. Endi