The San Bernardino shooting last Wednesday is being treated as an act of terrorism, said FBI Director, James Comey. Investigators are currently examining the digital footprints of the killers to determine who may have known about their plot.

The Washington Post reported that initially, officials were doubtful whether or not the shooting at the Inland Regional Center was considered terrorism or a case of workplace violence. However, when investigators discovered a Facebook post from one of the shooters, Tashfeen Malik, who, just after the shooting began, pledged her allegiance to one of the leaders of the Islamic State, Bakr al-Baghdadi.

A Facebook official who wished to remain anonymous, confirmed the posting, adding that the social media network removed the post a day after the attack, as content praising an Islamic State leader violates its community standards. The content, however, was available for a period of time, although the company is cooperating with law enforcement regarding the investigation.

A post on a blog linked to the Islamic State on Friday claimed that the attack was carried out by ISIS supporters. Malik and her husband, Syed Rizwan Farook, killed 14 people and wounded another 21 in the attack. Both shooters were killed in a gun fight with the police, later that same day.

Despite their allegiance to an Islamic State leader, the terrorist group -- who immediately claimed responsibility for several attacks over the past few weeks -- did not appear to do the same regarding the shooting that Malik and Farook had carried out, yet the shooting is treated as a terrorist attack all the same.

A search in the couple's residential town house showed an empty crib, a package of diapers, children's toys, personal documents, Arabic writings, and family photos, depicting what seemed to be the life of a normal family.

However, a staggering arsenal of firearms, ammunition, pipe bombs, and what is said to be virtually a bomb-making factory, were found along with the personal mementos, reported USA Today.

Interestingly, days after the attack, officials found that neither Farook nor Malik showed any outward signs of Islamist radicalization, psychological distress, or lust for mayhem. There is said to be no established link between the couple and the terrorist organization, and that neither of them were on any watch lists. A US law enforcement official also stated that although Farook was in contact with persons with possible ties to terrorism, his circle was not considered to have "substantial" contacts for them to carry out attacks in the name of the Islamic State.