WASHINGTON — The FBI is investigating a shooting that left 14 people dead and 21 wounded in San Bernardino, California, as an act of terrorism, it said Friday.
"As of today, based on information and the facts as we know them, we are now investigating these horrific acts as an act of terrorism," FBI Assistant Director David Bowdich said.
A "number of pieces of evidence" prompted the FBI to shift the focus of its investigation, he said, but that it remained unclear whether the suspects in the attack were directed or inspired by a terrorist group like Islamic State or al-Qaeda.
He pointed to the planning of the attack and attempts to destroy digital evidence, including the destruction of two mobile phones, but would not provide further details about what evidence pointed to terrorism.
FBI Director James Comey said however that there was no evidence that the alleged attackers, Tashfeen Malik, 29, and Syed Rizwan Farook, 28, were part of an organized terrorist group or cell.
"The investigation so far has developed evidence of radicalism by the killers and the potential for inspiration from a foreign terrorist organization," Comey said.
There was also no evidence the attackers had had meaningful contact with any individuals already being investigated by the FBI, he said.
Malik, the wife in the husband-wife pair suspected in the mass killing, had pledged allegiance to Islamic State in a Facebook post shortly before or during the attack, the FBI confirmed.
US broadcasters earlier reported that Malik posted the pledge under an alias and later deleted it.
Lawyers for the Farook family said the FBI had not found "any clear smoking gun" that the suspects were involved in terrorism and questioned allegations based on Facebook posts.
None of the family members had any idea that the attack was going to happen, lawyer David Chesley said.
Pakistani intelligence sources told dpa that Malik had had contact in the past with radical Islamic cleric, Maulana Abdul Aziz, at Islamabad's Red Mosque. A mosque spokesman said he could not confirm whether they had met.
Malik, and her husband, Farook, are accused of carrying out the attack on his colleagues in the county health department.
The couple were killed in a shootout with police hours after the massacre at a conference centre in the city east of Los Angeles.
The FBI is investigating the couple's digital and telephone communications and whether they may have been planning additional attacks with the large arsenal found in their apartment and car.
Farook, a US citizen, had spent time in Pakistan and Saudi Arabia, and his international contacts are now under investigation, Bowdich said earlier.
Farook returned to the United States from Saudi Arabia in July 2014 with Malik, who entered the country with a Pakistani passport on a K1 visa, available to fiancees of US citizens. The two later married.
The couple left their 6-month-old daughter with relatives prior to the attack under the pretense of going to a medical appointment, according to media reports.
Javier Lesaca, a terrorism expert at George Washington University, told dpa the attack would fit with Islamic State efforts to use social media and the internet to inspire so-called lone wolf terrorists to commit attacks abroad.
"They don't need a big structure just need to convince a few people around the world to be able to create a problem of global security," he said.
Officials had earlier said the motive in the attack was unclear, and US President Barack Obama said it could have been terrorism or workplace violence.
White House spokesman Josh Earnest earlier Friday wouldn't comment on details of the ongoing investigation and said it was too soon to draw conclusions about the attackers' motive.
Wearing black tactical gear but no body armour, the two assailants fired 65 to 75 rounds from "assault-style" rifles and left a bag containing three pipe bombs rigged to a remote-controlled toy car, which did not detonate, police said.
The search of the suspects' house, about 5 kilometres from the site of the shooting, uncovered about 5,000 rounds of ammunition and 12 pipe bombs, plus additional bomb-making material and tools, police said.
The San Bernardino massacre is the second major US mass shooting in less than a week. On November 27, a gunman killed three people and injured nine at a family planning clinic in Colorado.
Story: DPA / Anne K. Walters