UPDATE 2:56 p.m.: The FBI is treating the San Bernardino shooting as an act of terrorism in light of the developments that have occurred within the past 24 hours, according to the New York Times. 

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Law enforcement officials have revealed that Tashfeen Malik, who, along with her husband, carried out the San Bernardino mass shooting, pledged her allegiance to the leader of ISIS "just before the attack."

Malik, 27, along her husband, Syed Rizwan Farook, 28, were killed in a shootout hours after Wednesday's shooting at the Inland Regional Center that left 14 people dead. Marking the deadliest mass shooting the United States has experienced since the Sandy Hook shooting in 2012.

Malik, a Pakistani native who had been living in Saudi Arabia before she married Farook,  posted an online statement of support for Abu Bakr al-Baghdadi on Facebook, according to Reuters.

The investigation had long been focused on the motivation for the attack, with many, including President Barack Obama, suggesting that it was motivated by extremist ideology. Evidence continued to lean in that direction, including 12 pipes and 2,000 rounds of ammunition being found at their home.

As the investigation continues, authorities are looking to see if it was in fact Malik who had radicalized Farook,  according to NBC News.

However, based on testimony from former co-worker Christian Nwadike, who worked with U.S.-born Farook for five years, this might be the case.

"When he came back from Saudi Arabia, he started growing beards -- that was the change," Nwadike said, adding that he believes Malik helped radicalize Farook, according to CBS News. "Yes, by the wife, I think he married a terrorist."

Investigators are also reviewing the couple's computer and cellphone records to determine if they browsed jihadist websites or were in communication with any militant groups overseas.