Authorities don't yet know if Wednesday's deadly shooting rampage in San Bernardino, California, was an act of terrorism, but a statement from terror group Islamic State has called the suspected killers followers of the group.
The comment comes a day after the FBI said it was officially investigating the shooting, which left 14 people dead, as a possible terrorist act. But FBI Director James Comey noted Friday that there are no indications the husband and wife suspected of carrying out the massacre had any ties to known terrorist groups, adding that it was too soon to draw any conclusions.
"We are keeping our minds open," Comey said at a news conference. "There is a lot of evidence in this case that doesn't quite make sense."
President Obama will address the nation on Sunday at 8 p.m. ET, to discuss the shootings and what steps the government is taking to keep Americans safe, the White House said.
Law enforcement sources authorities told NBC News that suspect Tashfeen Malik, 27, posted a pledge of support to an ISIS leader on Facebook at around the time of the attack. On Saturday, ISIS's official radio station aired a statement saying the mass shooting was carried out by two "supporters" of the extremist group, according to Associated Press writer Maamoun Youssef. The message's authenticity was confirmed by NBC News.
"We ask God to accept them as martyrs," the statement said, according to a translation.
While praising the attack, the group stopped short of claiming responsibility for it. The Al-Bayan report Saturday echoed a claim carried Friday by the ISIS-affiliated Aamaq news agency, according to The AP.
Twenty-one people were also wounded in the massacre, at a health facility east of Los Angeles Wednesday morning where Malik's husband's workplace was holding a training session and office holiday party. The death toll is the highest in a U.S. shooting since 2012.
Malik and her husband, Syed Rizwan Farook, were killed in a shootout with police after a huge manhunt. Lawyers for the family of Farook said they were shocked to learn that the couple might have sympathized with terror groups, and suggested the shooting could well have been workplace related.
ISIS's radio report did not refer to Farook and Malik as actual members of the Islamic State group. Militants affiliated with ISIS who carry out attacks are commonly referred to in the group's propaganda as "lions," ''fighters" or "mujahedeen," according to The AP.
President Barack Obama was briefed on the latest in the investigation Saturday, according to the White House, which said the shooting remains Obama's highest priority.
"The President's team highlighted several pieces of information that point to the perpetrators being radicalized to violence to commit these heinous attacks. The President's team also affirmed that they had as of yet uncovered no indication the killers were part of an organized group or formed part of a broader terrorist cell," the statement read.
But federal investigators won't be able to sift through years of phone records that would have been available if the shooting had taken place just one week earlier. A court order made five years' worth of records for Farook and Malik off-limits, even if investigators had a warrant, The AP reported Saturday.
Meanwhile, investigations are underway over Malik's reported connections in the Middle East. She was born in Pakistan and met her husband in Saudi Arabia, according to federal officials.
Malik, 27, gained permanent residence status in the U.S. after marrying Farook; authorities believe they met when he was in Saudi Arabia while he was on the common Muslim pilgrimage to the country, the haj. Farook, 28, was born in Illinois and worked for the San Bernardino County health agency as an inspector.
They had a six-month-old daughter who is now in child protective custody, according to family members.
While some reports claimed Malik once met a cleric at the Red Mosque in Islamabad, Pakistan, a mosque spokesman told NBC News Saturday that the mosque and its personnel have no connection to her.
"This is a conspiracy by the media to drag our name into it", said the spokesman, Abdul Qadir.
Saudi authorities told The Associated Press there is no record of her ever being a resident there.